Methods of making acrylic acid from lactic acid or its derivatives in liquid phase

ABSTRACT

Methods for making acrylic acid, acrylic acid derivatives, or mixtures thereof by contacting a feed stream containing lactic acid, lactic acid derivatives, or mixtures thereof with a molten salt catalyst comprising an ionic liquid (IL) and an acid in liquid phase are provided.

FIELD OF THE INVENTION

The present invention generally relates to methods of making acrylicacid, acrylic acid derivatives, or mixtures thereof. Specifically, thepresent invention relates to methods of making acrylic acid, acrylicacid derivatives, or mixtures thereof by contacting a feed streamcontaining lactic acid, lactic acid derivatives, or mixtures thereofwith a molten salt catalyst in liquid phase.

BACKGROUND OF THE INVENTION

Acrylic acid, acrylic acid derivatives, or mixtures thereof are usedtoday in a variety of industrial materials, such as adhesives, binders,coatings, paints, polishes, detergents, flocculants, dispersants,thixotropic agents, sequestrants, and superabsorbent polymers (SAP),which are used in disposable absorbent articles, including diapers andhygienic products. In terms of production process, acrylic acid istypically made today from the two-step catalytic oxidation of propylene,which in turn is produced from fossil resources, such as petroleum ornatural gas. More on the oxidation of propylene to make acrylic acid andother production methods can be found in the Kirk-Othmer Encyclopedia ofChemical Technology, Vol. 1, pgs. 342-369 (5^(th) Ed., John Wiley &Sons, Inc., 2004).

Fossil-derived acrylic acid uses resources that are not renewable as ittakes hundreds of thousands of years to form naturally and only a shorttime to consume, and contributes to greenhouse emissions due to its highcontent of fossil-derived carbon. On the other hand, renewable resourcesrefer to materials that are produced via a natural process at a ratecomparable to their rate of consumption (e.g., within a 100-year timeframe) and can be replenished naturally or via agricultural techniques.Examples of renewable resources include plants, such as sugar cane,sugar beets, corn, potatoes, citrus fruit, woody plants, lignocellulose,carbohydrate, hemicellulose, cellulosic waste, animals, fish, bacteria,fungi, and forestry products. As fossil resources become increasinglyscarce, more expensive, and potentially subject to regulations for CO₂emissions, there exists a growing need for non-fossil-derived acrylicacid, acrylic acid derivatives, or mixtures thereof that can serve as analternative to fossil-derived acrylic acid, acrylic acid derivatives, ormixtures thereof.

Many attempts have been made over the last 80 years to makenon-fossil-derived acrylic acid, acrylic acid derivatives, or mixturesthereof from renewable resources, such as lactic acid (also known as2-hydroxypropionic acid) and other materials. From these resources, onlylactic acid is produced today in high yield and purity from sugar (≥90%of theoretical yield, or equivalently, ≥0.9 g of lactic acid per g ofsugar), and with economics which could support producing acrylic acidcost competitively to fossil-derived acrylic acid. As such, lactic acidor lactate presents a real opportunity of serving as a feedstock forbio-based acrylic acid, acrylic acid derivatives, or mixtures thereof.

The overwhelming majority of scientific literature and patent artdescribe the gas phase dehydration of lactic acid, lactic acidderivatives, or mixtures thereof to acrylic acid, acrylic acidderivatives, or mixtures thereof. However, liquid phase dehydrationshould offer significant advantages over the gas phase dehydration, forexample, lower operating temperature and pressure, longer residencetime, lower energy use and CO₂ emissions, wide selection of catalysttypes (e.g. homogeneous and heterogeneous) and catalysts to choose from,lower coking potential of the catalysts, lower safety concerns, lowerpotential for lactic acid corrosion, wider selection of reactor designs,etc. U.S. Pat. No. 9,309,180 (assigned to Evonik Industries AG)discloses a process to dehydrate lactic acid and produce acrylic acid inliquid phase with the use of various metal salt catalysts, such asK₂HPO₄, KH₂PO₄, BaHPO₄, and mixtures of similar salts. At 300° C. andreaction time ranging from 4.4 h to 5.5 h, the yield of acrylic acid wasbetween 0.1 mol % and 1.3 mol %.

Accordingly, there is a need for liquid phase dehydration methods oflactic acid, lactic acid derivatives, or mixtures thereof to acrylicacid, acrylic acid derivatives or mixtures thereof with high yield andselectivity.

SUMMARY OF THE INVENTION

In one embodiment of the present invention, a method of making acrylicacid, acrylic acid derivatives, or mixtures thereof is provided. Themethod comprises contacting a feed stream comprising lactic acid, lacticacid derivatives, or mixtures thereof with a molten salt catalyst in areactor at a temperature; wherein said molten salt catalyst comprises anionic liquid (IL) and an acid; and whereby acrylic acid, acrylic acidderivatives, or mixtures thereof are produced as a result of saidcontacting in said reactor.

In another embodiment of the present invention, a method of makingacrylic acid, acrylic acid derivatives, or mixtures thereof is provided.The method comprises contacting a feed stream comprising2-acetoxypropionic acid (2-APA) with a molten salt catalyst in a reactorat 220° C.; wherein said molten salt catalyst comprisestetrabutylphosphonium bromide ([PBu₄]Br) and pyrophosphoric acid(H₄P₂O₇) at a molar ratio of about 4.75; wherein said contactingproceeds under atmospheric pressure and in the presence of a strip gas;wherein said strip gas is argon; and whereby acrylic acid is produced asa result of said contacting in said reactor with a yield of at leastabout 30 mol %.

In yet another embodiment of the present invention, a method of makingacrylic acid, acrylic acid derivatives, or mixtures thereof is provided.The method comprises contacting a feed stream comprising 2-APA with amolten salt catalyst in a reactor at 220° C.; wherein said molten saltcatalyst comprises ethyltriphenylphosphonium bromide ([EtPPh₃]Br) andhydrobromic acid (HBr) at a molar ratio of about 4; wherein saidcontacting proceeds under atmospheric pressure; and whereby acrylic acidis produced as a result of said contacting in said reactor with anacrylic acid yield of at least about 25 mol %.

In even yet another embodiment of the present invention, a method ofmaking acrylic acid, acrylic acid deriuvatives, or mixtures thereof isprovided. The method comprises contacting a feed stream comprisinglactide with a molten salt catalyst in a reactor at 150° C.; whereinsaid molten salt catalyst comprises [PBu₄]Br and 2-bromopropionic acid(2-BrPA) at a molar ratio of about 20; wherein said contacting proceedsunder atmospheric pressure; and whereby acrylic acid is produced as aresult of said contacting in said reactor with an acrylic acid yield ofat least about 52 mol %.

DETAILED DESCRIPTION OF THE INVENTION I Definitions

As used herein, the term “fossil-derived” material refers to a materialthat is produced from fossil resources, such as crude oil (petroleum),natural gas, coal, peat, etc.

As used herein, the term “non-fossil-derived” material refers to amaterial that is produced from non-fossil resources. For clarity and forthe purposes of the present invention, the terms “renewable” material,“bio-based” material, “non-petroleum” material, and “non-fossil-derived”material are used interchangeably.

As used herein, the term “renewable” material refers to a material thatis produced from a renewable resource, which is a resource produced viaa natural process at a rate comparable to its rate of consumption (e.g.,within a 100 year time frame). The renewable resource can be replenishednaturally or via agricultural techniques. Non-limiting examples ofrenewable resources include plants (such as sugar cane, beets, corn,potatoes, citrus fruit, woody plants, lignocellulose, hemicellulose, andcellulosic waste), animals, fish, bacteria, fungi, and forestryproducts. These resources can be naturally occurring, hybrids, orgenetically engineered organisms. Fossil resources take longer than 100years to form and thus they are not considered renewable resources.

As used herein, the term “renewable content” refers to the amount ofcarbon from a renewable resource in a material as a percent of theweight (mass) of the total organic carbon in the material, as determinedby ASTM D6866-10 Method B.

As used herein, the term “chemically inert” material refers to amaterial which remains in the same chemical form, under equilibriumconditions, when contacted with another material or materials. In thecontext of the present invention, more than about 90 wt % of thematerial should remain in the same chemical form to be considered a“significantly chemically inert” material and more than about 98 wt % ofthe material should remain in the same chemical form to be considered an“essentially chemically inert” material.

As used herein, the term “strip gas” refers to a gas that is used tophysically separate one or more components from a liquid stream.Typically a strip gas is made to interact with a liquid stream in eitherco-current or counter-current flows to allow volatile components in theliquid stream to partition into the strip gas and be carried away by thegas stream for subsequent collection.

As used herein, the term “better leaving group” refers to a chemicalgroup attached to the α carbon position of lactic acid that can beremoved easier (e.g. milder operating conditions, or lower activationenergy, or faster removal rate, etc.) than the α carbon hydroxyl groupof lactic acid in a dehydration reaction. Better leaving groups arebetter able to stabilize the additional electron density that resultsfrom bond heterolysis than the hydroxide anion; i.e., better leavinggroups exhibit lower ΔG's for elimination than the ΔG for elimination ofthe hydroxide anion. A list of better leaving groups than the hydroxylgroup can be found in Table 10.10 of J. March, Advanced OrganicChemistry—Reactions, Mechanisms, and Structure, 4^(th) Ed., Wiley 1992,with specific examples of better leaving groups being: —N₂ ⁺, —OR₂ ⁺,—OSO₂F, OSO₂CF₃, —I, —Br, —Cl, —F, —OH₂ ⁺, —NH₃ ⁺, and —OAr.

As used herein, the terms “LA” refers to lactic acid, “AA” refers toacrylic acid, “AcH” refers to acetaldehyde, and “PA” refers to propionicacid.

As used herein, the term “IL” means a salt in the liquid state.

As used herein, the term “lactic acid equivalent” refers to the lacticacid mols contained within lactic acid, lactide, or mixtures thereof. Assuch, the lactic acid equivalent of 1 mol of lactic acid is 1 mol, thelactic acid equivalent of 1 mol of lactide is 2 mols of lactic acid, andthe lactic acid equivalent of 1 mol of a mixture of lactic acid andlactide depends on the mol fraction of lactic acid in the mixture.

As used herein, the term “conversion” in mol % is defined as [lacticacid, lactic acid derivatives, or mixtures thereof flow rate in(mol/min)−lactic acid, lactic acid derivatives, or mixtures thereof flowrate out (mol/min)]/[lactic acid, lactic acid derivatives, or mixturesthereof flow rate in (mol/min)]×100.

As used herein, the term “yield” in mol % is defined as [product flowrate out (mol/min)/lactic acid, lactic acid derivatives, or mixturesthereof flow rate in (mol/min)]×100.

As used herein, the term “selectivity” in mol % is defined as[Yield/Conversion]×100.

As used herein, the term “Weight Hourly Space Velocity” or “WHSV” in h⁻¹is defined as 60×[Total lactic acid flow rate (g/min)/catalyst weight(g)]. For the purpose of this definition, the catalyst weight does notinclude the weight of any inert support.

As used herein, the term “standard Gibbs free energy of formation ofoxide” in kJ/mol is defined as the change in Gibbs free energy thataccompanies the formation of 1 mol of oxide in its standard state fromits constituent elements in their standard states (1 bar pressure and298.15° K or 25° C.), as is well know to those skilled in the art. Thetypical notation for the standard Gibbs free energy is ΔG_(f) ⁰.

As used herein, the term “pK_(a)” is the negative base-10 logarithm ofthe acid dissociation constant of a solution of the acid in water at 25°C., as is well known to those skilled in the art.

As used herein, the terms “molten salt catalyst”, “reactor medium”, and“reaction medium” are used interchangeably.

II. Catalysts for the Dehydration of Lactic Acid or Its Derivatives toAcrylic Acid or Its Derivatives

Unexpectedly, it has been found that molten salt catalysts comprising anIL and an acid (either Lewis acid, Brønsted acid, or mixtures thereof)can dehydrate lactic acid, lactic acid derivatives, or mixtures thereofto acrylic acid, acrylic acid derivatives, or mixtures thereof with highyield and selectivity (i.e., low amount and few side products). The acidis soluble in the IL and the IL has a bromide anion (Br⁻). Furthermore,the Lewis acid is selected from the group consisting of CaBr₂, MgBr₂,AlBr₃, CuBr₂, and mixtures thereof, and the Brønsted acid has a pKa lessthan about 5 in water at 25° C. Although not wishing to be bound by anytheory, applicants hypothesize that the combination of the IL and acidcauses the substitution of the oxygen-containing group at the α carbonof lactic acid or lactic acid derivatives by the Br⁻ of the IL. The Br⁻is then either removed in a subsequent elimination reaction along with aproton from the β carbon or isomerized to the β carbon and then removedin a subsequent elimination reaction along with a proton from the αcarbon (the proton removal is assisted by the conjugate base of theacid) to form the double bond in acrylic acid or acrylic acidderivatives. Also, applicants hypothesize that the Lewis acid comprisesan oxophilic metal having a standard Gibbs free energy of oxideformation lower than about −600 kJmol and Br⁻ such that the net chargeof the Lewis acid is 0.

For the purposes of the present invention, the term “molten saltcatalyst” refers to a catalyst that comprises an IL and an acid. ILs aresalts in the liquid state, and in some context, the term refers to saltswith a melting temperature below the boiling point of water. Whiletypical liquids are made of electrically neutral molecules, ILs areprimarily made of poorly-coordinated ions and short-lived ion pairs.Other names for ILs found in the literature are “room temperature moltensalts”, “low temperature molten salts”, “ambient temperature moltensalt”, “ionic melts”, “ionic fluids”, “fused salts”, “ionic glasses”,“liquid electrolytes”, and “liquid organic salt”. Non-limiting examplesof ILs are 1-ethyl-3-methylimidazolium chloride,1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazoliummethanesulfonate, 1-butyl-3-methylimidazolium methanesulfonate,methylimidazolium chloride, 1-ethyl-3-methylimidazolium acetate,1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazoliumthiocyanate, 1-butyl-3-methylimidazolium hexafluorophosphate,1-ethyl-3-methylimidazolium tetrafluoroborate, tetrabutylphosphoniumbromide, tetrabutylammonium bromide, 1-butylpyridinium bromide,1-butyl-1-methylpyrrolidinium chloride, and tetrahexylammonium iodide.

As salts, ILs have an anion and a cation. In one embodiment of thepresent invention, said IL has an organic cation. In another embodimentof the present invention, said IL has an organic cation selected fromthe group consisting of imidazolium, pyridinium, pyrrolidinium,ammonium, phosphonium, their derivatives, and mixtures thereof. In yetanother embodiment of the present invention, said IL has a phosphoniumcation. In even yet another embodiment of the present invention, saidphosphonium cation is selected from the group consisting of alkylsubstituted phosphonium cations, aryl substituted phosphonium cations,mixed alkyl aryl substituted phosphonium cations, and mixtures thereof.Non-limiting examples of alkyl substituted phosphonium cations aretetrabutylphosphonium, tributylethylphosphonium,dibutyldiethylphosphonium, and butyltriethylphosphonium. Non-limitingexamples of aryl substituted phosphonium cations aretetraphenylphosphonium, triphenyl-p-tolylphosphonium,diphenyl-di-p-tolylphosphonium, phenyl-tri-p-tolylphosphonium, andtetra-p-tolylphosphonium. Non-limiting examples of alkyl arylsubstituted phosphonium cations are ethyltriphenylphosphonium,diethydiphenylphosphonium, triethylphenylphosphonium,tributylphenylphosphonium, and tributyl-p-tolylphosphonium. In oneembodiment of the present invention, said IL has a tetrabutylphosphoniumcation. In another embodiment of the present invention, said IL has anethyltriphenylphosphonium cation. In another embodiment of the presentinvention, said IL has an organic anion. In yet another embodiment ofthe present invention, said organic anion is selected from the groupconsisting of alkylsulfate, tosylate, methanesulfonate, and mixturesthereof. In one embodiment of the present invention, said IL has aninorganic anion. In another embodiment of the present invention, saidinorganic anion is selected from the group consisting of chloride (Cl⁻),bromide (Br⁻), iodide (I⁻), tetrafluoroborate (BF₄ ⁻),hexafluorophosphate (PF₆ ⁻), bis(trifluoromethylsulfonyl)amide, andmixtures thereof. In yet another embodiment of the present invention,said inorganic anion is bromide (Br⁻). In even yet another embodiment ofthe present invention, said IL has a bromide (Br⁻) anion and aphosphonium cation. In one embodiment of the present invention, said ILis tetrabutylphosphonium bromide ([PBu₄]Br). In another embodiment ofthe present invention, said IL is ethyltriphenylphosphonium bromide([EtPPh₃]Br).

In one embodiment of the present invention, said acid is soluble in saidIL and selected from the group consisting of Lewis acid, Brønsted acid,and mixtures thereof. In another embodiment of the present invention,said acid is a Brønsted acid. In yet another embodiment of the presentinvention, said Brønsted acid has a pK_(a) less than about 5 in water at25° C. Non-limiting examples of Brønsted acids with a pK_(a) less thanabout 5 in water at 25° C. are acetic acid (CH₃CO₂H), phosphoric acid(H₃PO₄), pyrophosphoric acid (H₄P₂O₇), sulfuric acid (H₂SO₄),hydrobromic acid (HBr), 2-bromopropionic acid (2-BrPA), 3-bromopropionicacid (3-BrPA), hydrochloric acid (HCl), and nitric acid (HNO₃). In oneembodiment of the present invention, said Brønsted acid ispyrophosphoric acid (H₄P₂O₇). In another embodiment of the presentinvention, said Brønsted acid is hydrobromic acid (HBr). In yet anotherembodiment of the present invention, said Brønsted acid is sulfuric acid(H₂SO₄). In even yet another embodiment of the present invention, saidBrønsted acid is phosphoric acid (H₃PO₄). In one embodiment of thepresent invention, said Brønsted acid is acetic acid (CH₃CO₂H). Inanother embodiment of the present invention, said Brønsted acid is2-bromopropionic acid (2-BrPA). In yet another embodiment of the presentinvention, said Brønsted acid is 3-bromopropionic acid (3-BrPA). In oneembodiment of the present invention, said 2-bromoprionic acid isprepared by the reaction of lactic acid or lactide and3-methyl-1-(4-butane sulfonic acid) imidazolium bromide ([MIMBS]Br). Inanother embodiment of the present invention, said 2-bromoprionic acid isprepared by the reaction of lactic acid or lactide and3-methyl-1-(4-butane sulfonic acid) imidazolium bromide ([MIMBS]Br) at atemperature from about 100° C. to about 140° C., at a molar ratio of[MIMBS]Br to lactic acid from about 1:1 to about 6:1, and reaction timeof about 5 hours.

In one embodiment of the present invention, said acid is a Lewis acid.In another embodiment of the present invention, said acid is a mixtureof a Lewis acid and a Brønsted acid. In yet another embodiment of thepresent invention, said Lewis acid is selected from the group consistingof CaBr₂, MgBr₂, AlBr₃, CuBr₂, and mixtures thereof. In even yet anotherembodiment of the present invention, said Lewis acid comprises anoxophilic metal having a standard Gibbs free energy of oxide formationlower than about −600 kJmol and Br⁻ such that the net charge of theLewis acid is 0. Non-limiting examples of Lewis acids comprising anoxophilic metal having a standard Gibbs free energy of oxide formationlower than about −600 kJmol and Br⁻ such that the net charge of theLewis acid is 0 are CaBr₂, MgBr₂, AlBr₃, BaBr₂, SiBr₄, BeBr₂, CrBr₆, andWBr₆.

In one embodiment of the present incention, the oxophilic metal has anoxidation state ranging from +1 to +6. In another embodiment of thepresent invention, the oxophilic metal has an oxidation state of +2 or+3. In yet another embodiment of the present invention, the oxophilicmetal has an oxidation state of +4 or +5 or +6.

In one embodiment of the present invention, the molar ratio of saidBrønsted acid to said Lewis acid is between about 0.1 and about 10. Inyet another embodiment of the present invention, the molar ratio of saidBrønsted acid to said Lewis acid is between about 0.5 and about 5. Ineven yet another embodiment of the present invention, the molar ratio ofsaid Brønsted acid to said Lewis acid is about 1.

In one embodiment of the present invention, said IL istetrabutylphosphonium bromide ([PBu₄]Br) and said acid is pyrophosphoricacid (H₄P₂O₇). In another embodiment of the present invention, said ILis tetrabutylphosphonium bromide ([PBu₄]Br) and said acid is acetic acid(CH₃CO₂H). In yet another embodiment of the present invention, said ILis [PBu₄]Br and said acid is selected from the group consisting ofCaBr₂, MgBr₂, AlBr₃, CuBr₂, and mixtures thereof. In even yet anotherembodiment of the present invention, said IL is tetrabutylphosphoniumbromide ([PBu₄]Br) and said acid is sulfuric acid (H₂SO₄). In oneembodiment of the present invention, said IL is tetrabutylphosphoniumbromide ([PBu₄]Br) and said acid is hydrobromic acid (HBr). In anotherembodiment of the present invention, said IL is ethyltriphenlphosphoniumbromide ([EtPPh₃]Br) and said acid is hydrobromic acid (HBr). In yetanother embodiment of the present invention, said IL istetrabutylphosphonium bromide ([PBu₄]Br) and said acid consists of HBrand a Lewis acid selected from the group consisting of CaBr₂, MgBr₂,AlBr₃, CuBr₂, and mixtures thereof. In even yet another embodiment ofthe present invention, said IL is tetrabutylphosphonium bromide([PBu₄]Br) and said acid is 2-bromopropionic acid (2-BrPA). In oneembodiment of the present invention, said IL is tetrabutylphosphoniumbromide ([PBu₄]Br) and said acid is 3-bromopropionic acid (3-BrPA).

In one embodiment of the present invention, the molar ratio of said ILto said acid is between about 1 and about 30. In another embodiment ofthe present invention, the molar ratio of said IL to said acid isbetween about 2 and about 15. In yet another embodiment of the presentinvention, the molar ratio of said IL to said acid is between about 3and about 7. In even yet another embodiment of the present invention,the molar ratio of said IL to said acid is about 4. In one embodiment ofthe present invention, the molar ratio of said IL to said acid is about4.75. In another embodiment of the present invention, the molar ratio ofsaid IL to said acid is about 10. In yet another embodiment of thepresent invention, the molar ratio of said IL to said acid is about 20.

In one embodiment of the present invention, the molar ratio of said[PBu₄]Br and said H₄P₂O₇ is between about 1 and about 30. In anotherembodiment of the present invention, the molar ratio of said [PBu₄]Brand said H₄P₂O₇ is between about 3 and about 10. In yet anotherembodiment of the present invention, the molar ratio of said [PBu₄]Brand said H₄P₂O₇ is between about 3.5 and about 7. In even yet anotherembodiment of the present invention, the molar ratio of said [PBu₄]Brand said H₄P₂O₇ is about 4.75.

In one embodiment of the present invention, the molar ratio of said[PBu₄]Br and said HBr is between about 1 and about 20. In anotherembodiment of the present invention, the molar ratio of said [PBu₄]Brand said HBr is between about 2 and about 10. In yet another embodimentof the present invention, the molar ratio of said [PBu₄]Br and said HBris between about 2 and about 5. In even yet another embodiment of thepresent invention, the molar ratio of said [PBu₄]Br and said HBr isabout 4.75.

In one embodiment of the present invention, the molar ratio of said[EtPPh₃]Br and said HBr is between about 1 and about 20. In anotherembodiment of the present invention, the molar ratio of said [EtPPh₃]Brand said HBr is between about 2 and about 10. In yet another embodimentof the present invention, the molar ratio of said [EtPPh₃]Br and saidHBr is between about 2 and about 5. In even yet another embodiment ofthe present invention, the molar ratio of said [EtPPh₃]Br and said HBris about 4.

In one embodiment of the present invention, the molar ratio of said[PBu₄]Br and said H₂SO₄ is between about 3 and about 10. In anotherembodiment of the present invention, the molar ratio of said [PBu₄]Brand said H₂SO₄ is between about 3.5 and about 7. In yet anotherembodiment of the present invention, the molar ratio of said [PBu₄]Brand said H₂SO₄ is between about 4 and about 5. In even yet anotherembodiment of the present invention, the molar ratio of said [PBu₄]Brand said H₂SO₄ is about 4.75.

In one embodiment of the present invention, the molar ratio of said[PBu₄]Br and said H₃PO₄ is between about 3 and about 10. In anotherembodiment of the present invention, the molar ratio of said [PBu₄]Brand said H₃PO₄ is between about 3.5 and about 7. In yet anotherembodiment of the present invention, the molar ratio of said [PBu₄]Brand said H₃PO₄ is between about 4 and about 5. In even yet anotherembodiment of the present invention, the molar ratio of said [PBu₄]Brand said H₃PO₄ is about 4.75.

In one embodiment of the present invention, the molar ratio of said[PBu₄]Br and said acetic acid (CH₃CO₂H) is between about 3 and about 10.In another embodiment of the present invention, the molar ratio of said[PBu₄]Br and said acetic acid (CH₃CO₂H) is between about 3.5 and about7. In yet another embodiment of the present invention, the molar ratioof said [PBu₄]Br and said acetic acid (CH₃CO₂H) is between about 4 andabout 5. In even yet another embodiment of the present invention, themolar ratio of said [PBu₄]Br and said acetic acid (CH₃CO₂H) is about4.75.

In one embodiment of the present invention, the molar ratio of said[PBu₄]Br and said 2-bromopropionic acid (2-BrPA) is about 10. In anotherembodiment of the present invention, the molar ratio of said [PBu₄]Brand said 2-bromopropionic acid (2-BrPA) is about 20. In yet anotherembodiment of the present invention, the molar ratio of said [PBu₄]Brand said 3-bromopropionic acid (3-BrPA) is about 10. In even yet anotherembodiment of the present invention, the molar ratio of said [PBu₄]Brand said 3-bromopropionic acid (3-BrPA) is about 20.

In one embodiment of the present invention, the molar ratio of said[PBu₄]Br and said CaBr₂ is about 4.75. In another embodiment of thepresent invention, the molar ratio of said [PBu₄]Br and said MgBr₂ isabout 4.75. In yet another embodiment of the present invention, themolar ratio of said [PBu₄]Br and said AlBr₃ is about 4.75. In even yetanother embodiment of the present invention, the molar ratio of said[PBu₄]Br and said CuBr₂ is about 4.75. In one embodiment of the presentinvention, the molar ratio of said [PBu₄]Br and said equimolar mixtureof HBr and AlBr₃ is about 4.75. In another embodiment of the presentinvention, the molar ratio of HBr and AlBr₃ is between about 0.1 andabout 10. In yet another embodiment of the present invention, the molarratio of HBr and AlBr₃ is between about 0.5 and about 5. In even yetanother embodiment of the present invention, the molar ratio of HBr andAlBr₃ is about 1.

In one embodiment of the present invention, the molten salt catalystcomprising an IL and an acid further comprises other compound which issignificantly chemically inert to said IL and acid. In anotherembodiment of the present invention, said other compound comprises acation and an anion. Non-limiting examples of anions in the othercompound are arsenates, condensed arsenates, nitrates, sulfates,condensed sulfates, borates, carbonates, chromates, condensed chromates,vanadates, niobates, tantalates, selenates, condensed silicates,condensed aluminates, germanates, condensed germanates, molybdates,condensed molybdates, other monomeric oxyanions, polyoxyanions,heteropolyphosphates, such as arsenatophosphates, phosphoaluminates,phosphoborates, phosphochromates, phosphomolybdates, phosphosilicates,phosphosulfates, phosphotungstates, and phosphate adducts, such asphosphate anions with telluric acid, halides, borates, carbonates,nitrates, sulfates, chromates, silicates, oxalates, mixtures thereof, orothers that may be apparent to those having ordinary skill in the art.

In one embodiment of the present invention, said molten salt catalystfurther comprises an inert support. Non-limiting examples of inertsupports are silica, silicate, alumina, aluminate, aluminosilicate,titania, titanate, zirconia, zirconate, carbon (such as activatedcarbon, diamond, graphite, or fullerenes), sulfate, phosphate,tantalate, ceria, other metal oxides, and mixtures thereof. In anotherembodiment of the present invention, said inert support consistsessentially of silica. In yet another embodiment of the presentinvention, said silica is selected from the group consisting ofamorphous silica, quartz, tridymite, cristobalite, moganite, coesite,and mixtures thereof. In even yet another embodiment of the presentinvention, said silica is amorphous silica. In one embodiment of thepresent invention, said silica has a specific surface area of less thanabout 10 m²/g. In another embodiment of the present invention, the inertsupport represents an amount between about 20 wt % and about 90 wt %,based on the total weight of the active catalyst.

In one embodiment of the present invention, the weight of the IL andacid based on the total weight of the molten salt catalyst is about 100wt %. In another embodiment of the present invention, the weight of theIL and acid based on the total weight of the molten salt catalyst isbetween about 5 wt % and about 90 wt %. In yet another embodiment of thepresent invention, the weight of the IL and acid based on the totalweight of the molten salt catalyst is between about 20 wt % and about 80wt %. In even yet another embodiment of the present invention, theweight of the IL and acid based on the total weight of the molten saltcatalyst is between about 40 wt % and about 60 wt %. In one embodimentof the present invention, the weight of the IL and acid based on thetotal weight of the molten salt catalyst is about 50 wt %.

In one embodiment of the present invention, the catalyst for makingacrylic acid, acrylic acid derivatives, or mixtures thereof is a moltensalt and comprises an IL and an acid. In another embodiment of thepresent invention, the catalyst for making acrylic acid, acrylic acidderivatives, or mixtures thereof is a molten salt and comprises an ILand an acid; wherein the IL is tetrabutylphosphonium bromide ([PBu₄]Br)and the acid is pyrophosphoric acid (H₄P₂O₇); wherein the molar ratio of[PBu₄]Br and H₄P₂O₇ is about 4.75; and whereby the acrylic acid isproduced with a yield of at least about 30 mol %. In yet anotherembodiment of the present invention, the catalyst for making acrylicacid, acrylic acid derivatives, or mixtures thereof is a molten salt andcomprises an IL and an acid; wherein the IL is tetrabutylphosphoniumbromide ([PBu₄]Br) and the acid is hydrobromic acid (HBr); wherein themolar ratio of [PBu₄]Br and HBr is between about 2 and about 5; andwhereby the acrylic acid is produced with a yield of at least about 18mol %. In yet another embodiment of the present invention, a catalystfor making acrylic acid, acrylic acid derivatives, or mixtures thereofby dehydrating lactic acid, lactic acid derivatives, or mixturesthereof; wherein said catalyst is a molten salt and comprises an IL andan acid; wherein said IL is ethyltriphenylphosphonium bromide([EtPPh₃]Br) and said acid is hydrobromic acid (HBr); wherein the molarratio of said [EtPPh₃]Br to said HBr is between about 2 and about 5; andwhereby said acrylic acid is produced with a yield of at least about 25mol %. In even yet another embodiment of the present invention, thecatalyst for making acrylic acid, acrylic acid derivatives, or mixturesthereof is a molten salt and comprises an IL and an acid; wherein the ILis tetrabutylphosphonium bromide ([PBu₄]Br) and the acid is2-bromopropionic acid (2-BrPA); wherein the molar ratio of [PBu₄]Br and2-BrPA is about 10; and whereby the acrylic acid is produced with ayield of at least about 47 mol %. In even yet another embodiment of thepresent invention, the catalyst for making acrylic acid, acrylic acidderivatives, or mixtures thereof is a molten salt and comprises an ILand an acid; wherein the IL is tetrabutylphosphonium bromide ([PBu₄]Br)and the acid is 3-bromopropionic acid (3-BrPA); wherein the molar ratioof [PBu₄]Br and 3-BrPA is about 10; and whereby the acrylic acid isproduced with a yield of at least about 47 mol %. In one embodiment ofthe present invention, the catalyst for making acrylic acid, acrylicacid derivatives, or mixtures thereof is a molten salt and comprises anIL and an acid; wherein the IL is tetrabutylphosphonium bromide([PBu₄]Br) and the acid is 2-bromopropionic acid (2-BrPA); wherein themolar ratio of [PBu₄]Br and 2-BrPA is about 20; and whereby the acrylicacid is produced with a yield of at least about 52 mol %. In even yetanother embodiment of the present invention, the catalyst for makingacrylic acid, acrylic acid derivatives, or mixtures thereof is a moltensalt and comprises an IL and an acid; wherein the IL istetrabutylphosphonium bromide ([PBu₄]Br) and the acid is3-bromopropionic acid (3-BrPA); wherein the molar ratio of [PBu₄]Br and3-BrPA is about 20; and whereby the acrylic acid is produced with ayield of at least about 52 mol %.

Besides an IL and an acid, the molten salt catalyst of the presentinvention can include a phospine oxide OPX₃, where X can be selectedfrom a variety of groups. Non-limiting examples of phosphine oxides aretriphenylphosphine oxide (TPPO), tributylphosphine oxide (TBPO),triethylphosphine oxide (TEPO), and trioctylphosphine oxide (TOPO).

The molten salt catalyst of the present invention can be utilized tocatalyze several chemical reactions. Non-limiting examples of reactionsare: dehydration of lactic acid, lactic acid derivatives, or mixturesthereof to acrylic acid; dehydration of 3-hydroxypropionic acid,3-hydroxypropionic acid derivatives, or mixtures thereof to acrylicacid; dehydration of glycerin to acrolein; isomerization of lactic acidto 3-hydroxypropionic acid in the presence of water; reduction ofhydroxypropionic acid to propionic acid or 1-propanol in the presence ofhydrogen gas; dehydration of aliphatic alcohols to alkenes or olefins;dehydrogenation of aliphatic alcohols to ethers; other dehydrogenations,hydrolyses, alkylations, dealkylations, oxidations, disproportionations,esterifications, cyclizations, isomerizations, condensations,aromatizations, polymerizations; and other reactions that may beapparent to those having ordinary skill in the art.

III Methods of Making Acrylic Acid, Acrylic Acid Derivatives, orMixtures Thereof

A method of dehydrating hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof to acrylic acid, acrylic acidderivatives, or mixtures thereof is provided. In one embodiment of thepresent invention, said hydroxypropionic acid is selected from the groupconsisting of lactic acid (2-hydroxypropionic acid), 3-hydroxypropionicacid, and mixtures thereof; and said hydroxypropionic acid derivativesare selected from the group consisting of lactic acid derivatives,3-hydroxypropionic acid derivatives, and mixtures thereof.

In another embodiment of the present invention, said hydroxypropionicacid is lactic acid and said hydroxypropionic acid derivatives arelactic acid derivatives. Lactic acid can be D-lactic acid, L-lacticacid, or mixtures thereof (including racemic mixture). It is well knownto those skilled in the art that the α carbon hydroxyl group of lacticacid is not a good leaving group and that the carboxylic group of lacticacid is prone to decarboxylation or decarbonylation. Thisdecarboxylation and decarbonylation is easier than the removal of thehydroxyl group, and that is the reason that many past attempts failed toproduce commercially-viable quantities of acrylic acid. Although notwishing to be bound by any theory, applicants believe thatcommercially-viable quantities of acrylic acid can be produced fromlactic acid if the hydroxyl group is replaced by a better leaving group,the carboxylic group is protected, or both the hydroxyl group isreplaced by a better leaving group and the carboxylic group isprotected.

Non-limiting examples of lactic acid derivatives with their carboxylicgroup protected are metal or ammonium salts of lactic acid (also calledmetal or ammonium lactates), alkyl esters of lactic acid (also calledalkyl lactates), cyclic di-esters of lactic acid, or mixtures thereof.Non-limiting examples of metal lactates are sodium lactate, potassiumlactate, and calcium lactate; non-limiting examples of alkyl lactatesare methyl lactate (MLA), ethyl lactate (ELA), butyl lactate, and2-ethylhexyl lactate; and a non-limiting example of cyclic di-esters oflactic acid is dilactide (also called lactide).

Non-limiting examples of lactic acid derivatives with their hydroxylgroup replaced by a better leaving group are 2-alkoxypropionic acids,2-aryloxypropionic acids, 2-acyloxypropionic acids, 2-fluoropropionicacid (2-FPA), 2-chloropropionic acid (2-ClPA), 2-bromopropionic acid(2-BrPA), 2-iodopropionic acid (2-IPA), or mixtures thereof.Non-limiting examples of 2-alkoxypropionic acids are 2-methoxypropionicacid and 2-ethoxypropionic acid; a non-limiting example of2-aryloxypropionic acid is 2-phenoxypropionic acid; and non-limitingexamples of 2-acyloxypropionic acid is 2-acetoxypropionic acid (2-APA)and 2-trifluoroacetoxypropionic acid (2-TFPA).

Non-limiting examples of lactic acid derivatives with both theirhydroxyl group replaced by a better leaving group and their carboxylicgroup protected are alkyl esters of 2-alkoxypropionic acid, alkyl estersof 2-aryloxypropionic acid, alkyl esters of 2-acyloxypropionic acid, ormixtures thereof. Non-limiting examples of alkyl esters of2-alkoxypropionic acid are ethyl 2-methoxypropionate and methyl2-ethoxypropionate; non-limiting examples of alkyl esters of2-aryloxypropionic acid are methyl 2-phenoxypropionate and ethyl2-phenoxypropionate; and non-limiting examples of alkyl esters of2-acyloxypropionic acid are methyl 2-acetoxypropionate (MAPA), ethyl2-acetoxypropionate (EAPA), and ethyl 2-trifluoacetoxypropionate (ETFP).

In one embodiment of the present invention, the lactic acid derivativesare selected from the group consisting of lactic acid with itscarboxylic group protected, lactic acid with its hydroxyl group replacedby a better leaving group, lactic acid with both its carboxylic groupprotected and hydroxyl group replaced by a better leaving group, andmixtures thereof. In another embodiment of the present invention, thelactic acid derivatives are selected from the group consisting oflactide, 2-acetoxypropionic acid (2-APA), ETFP, and 2-bromopropionicacid (2-BrPA). In yet another embodiment of the present invention, thelactic acid derivative is ETFP. Other lactic acid derivatives can belactic acid oligomers, lactic acid anhydride, and 3-bromopropionic acid(3-BrPA).

Lactic acid can be in monomeric form or as oligomers in said feedstream. In one embodiment of the present invention, the oligomers of thelactic acid in said feed stream are less than about 30 wt % based on thetotal amount of lactic acid, lactic acid derivatives, or mixturesthereof. In another embodiment of the present invention, the oligomersof the lactic acid in said feed stream are less than about 10 wt % basedon the total amount of lactic acid, lactic acid derivatives, or mixturesthereof. In yet another embodiment of the present invention, theoligomers of the lactic acid feed stream are less than about 5 wt %based on the total amount of lactic acid, lactic acid derivatives, ormixtures thereof. In even yet another embodiment of the presentinvention, the lactic acid is essentially in monomeric form in said feedstream.

The process to remove the oligomers from the feed stream can comprise apurification step or hydrolysis by heating step. In one embodiment ofthe present invention, the heating step can involve heating the feedstream at a temperature between about 50° C. and about 100° C. tohydrolyze the oligomers of the lactic acid. In another embodiment of thepresent invention, the heating step can involve heating the feed streamat a temperature between about 95° C. and about 100° C. to hydrolyze theoligomers of the lactic acid. In yet another embodiment of the presentinvention, the heating step can involve heating the feed stream at atemperature between about 50° C. and about 100° C. to hydrolyze theoligomers of the lactic acid and produce a monomeric lactic acid feedstream comprising at least 80 wt % of lactic acid in monomeric formbased on the total amount of lactic acid, lactic acid derivatives, ormixtures thereof. In even yet another embodiment of the presentinvention, the heating step can involve heating the feed stream at atemperature between about 50° C. and about 100° C. to hydrolyze theoligomers of the lactic acid and produce a monomeric lactic acid feedstream comprising at least 95 wt % of lactic acid in monomeric formbased on the total amount of lactic acid, lactic acid derivatives, ormixtures thereof. In one embodiment of the present invention, an about88 wt % aqueous solution of lactic acid, lactic acid derivatives, ormixtures thereof is diluted with water and the oligomers are hydrolyzedto produce an aqueous solution of about 20 wt % lactic acid.

3-hydroxypropionic acid derivatives can be metal or ammonium salts of3-hydroxypropionic acid, alkyl esters of 3-hydroxypropionic acid,3-hydroxypropionic acid oligomers, 3-alkoxypropionic acids or theiralkyl esters, 3-aryloxypropionic acids or their alkyl esters,3-acyloxypropionic acids or their alkyl esters, or a mixture thereof.Non-limiting examples of metal salts of 3-hydroxypropionic acid aresodium 3-hydroxypropionate, potassium 3-hydroxypropionate, and calcium3-hydroxypropionate. Non-limiting examples of alkyl esters ofhydroxypropionic acid are methyl 3-hydroxypropionate, ethyl3-hydroxypropionate, butyl 3-hydroxypropionate, 2-ethylhexyl3-hydroxypropionate, and mixtures thereof. Non-limiting examples of3-alkoxypropionic acids are 3-methoxypropionic acid and3-ethoxypropionic acid. A non-limiting example of 3-aryloxypropionicacid is 3-phenoxypropionic acid. A non-limiting example of3-acyloxypropionic acid is 3-acetoxypropionic acid.

Hydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof can be produced by sugar fermentation or chemical conversion ofsugars or other feedstock materials, such as glycerin. Nearly all worldproduction of lactic acid is by sugar fermentation today; however, thereare chemical conversion technologies currently in pilot or demo scale.Also, the sugar feedstock can be generation 1 sugar (i.e., sugar fromcorn, sugarcane, sugar beets, wheat, potato, rice, etc.) or generation 2sugar (i.e., sugar from the hydrolysis of biomass or agricultural waste,such as bagasse, corn stover, rice husk, wheat straw, etc.).

Acrylic acid derivatives can be metal or ammonium salts of acrylic acid,alkyl esters of acrylic acid, acrylic acid oligomers, or mixturesthereof. Non-limiting examples of metal salts of acrylic acid are sodiumacrylate, potassium acrylate, and calcium acrylate. Non-limitingexamples of alkyl esters of acrylic acid are methyl acrylate, ethylacrylate, butyl acrylate, 2-ethylhexyl acrylate, or mixtures thereof.

In one embodiment of the present invention, the feed stream comprises aliquid. In another embodiment of the present invention, the feed streamcomprises a solid. In yet another embodiment of the present invention,the feed stream comprises a liquid and a solid. In even yet anotherembodiment of the present invention, the feed stream comprises a liquidand a gas.

In one embodiment of the present invention, a method of making acrylicacid, acrylic acid derivatives, or mixtures thereof comprises contactinga feed stream comprising lactic acid, lactic acid derivatives, ormixtures thereof with a molten salt catalyst in a reactor at atemperature, wherein the molten salt catalyst comprises an IL and anacid, and whereby acrylic acid, acrylic acid derivatives, or mixturesthereof are produced as a result of the dehydration in the reactor.

In another embodiment of the present invention, said feed stream furthercomprises an essentially chemically inert diluent. In the context of thepresent invention, an essentially chemically inert diluent is anydiluent that is essentially chemically inert to said hydroxypropionicacid, hydroxypropionic acid derivatives, or mixtures thereof, but notnecessarily to said molten salt catalyst. Non-limiting examples ofessentially chemically inert diluents are water, hydrocarbons,chlorinated hydrocarbons, brominated hydrocarbons, fluorinatedhydrocarbons, esters, ethers, ketones, and mixtures thereof.Non-limiting examples of hydrocarbons are C5 to C8 linear and branchedalkanes. A non-limiting example of esters is ethyl acetate. Anon-limiting example of ethers is diphenyl ether. A non-limiting exampleof ketones is acetone. In yet another embodiment of the presentinvention, said essentially chemically inert diluent comprises water. Ineven yet another embodiment of the present invention, said essentiallychemically inert diluent consists essentially of water. In oneembodiment of the present invention said feed stream consistsessentially of hydroxypropionic acid, hydroxypropionic acid derivatives,or mixtures thereof.

In another embodiment of the present invention, the feed streamcomprising hydroxypropionic acid, hydroxypropionic acid derivatives, ormixtures thereof can further comprise one or more antioxidants. Inanother embodiment of the present invention, the feed stream comprisinghydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof further comprises butylated hydroxy toluene (BHT), butylatedhydroxy anisole (BHA), or mixtures thereof. In yet another embodiment ofthe present invention, the feed stream comprising hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof further comprisesethylene glycol, ethanedithiol, methanol, methanethiol, or mixturesthereof.

In one embodiment of the present invention, the concentration of thehydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof in said feed stream is between about 1 wt % and about 100 wt %.In another embodiment of the present invention, the concentration of thehydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof in said feed stream is between about 5 wt % and about 95 wt %.In yet another embodiment of the present invention, the concentration ofthe hydroxypropionic acid, hydroxypropionic acid derivatives, ormixtures thereof in said feed stream is between about 20 wt % and about80 wt %. In even yet another embodiment of the present invention, theconcentration of the hydroxypropionic acid, hydroxypropionic acidderivatives, or mixtures thereof in said feed stream is about 25 wt %.In one embodiment of the present invention, the concentration of thehydroxypropionic acid, hydroxypropionic acid derivatives, or mixturesthereof in said feed stream is about 50 wt %.

In one embodiment of the present invention, the concentration of thelactic acid, lactic acid derivatives, or mixtures thereof in said feedstream is between about 1 wt % and about 100 wt %. In another embodimentof the present invention, the concentration of the lactic acid, lacticacid derivatives, or mixtures thereof in said feed stream is betweenabout 5 wt % and about 95 wt %. In yet another embodiment of the presentinvention, the concentration of the lactic acid, lactic acidderivatives, or mixtures thereof in said feed stream is between about 20wt % and about 80 wt %. In even yet another embodiment of the presentinvention, the concentration of the lactic acid, lactic acidderivatives, or mixtures thereof in said feed stream is about 25 wt %.In one embodiment of the present invention, the concentration of thelactic acid, lactic acid derivatives, or mixtures thereof in said feedstream is about 50 wt %.

Non-limiting examples of reactors suitable for use in the presentinvention are static reactors, stirred tank reactors, recirculationreactors, trickle bed reactors, and combinations thereof. In oneembodiment of the present invention, the reactor is a stirred tankreactor. In another embodiment of the present invention, the stirredtank reactor is a single-layer reactor. A single-layer reactor consistsof a single layer (also called wall) that extends from the inner surfaceto the outer surface and has a wall thickness. The inner surface is incontact with the molten salt catalyst, the feed stream, and the productstream. In one embodiment of the present invention, the single-layerreactor comprises a wall, an outer surface, and an inner surface;wherein said wall is made from a wall material, has a wall thickness,and extends from said outer surface to said inner surface; and whereinsaid inner surface is in contact with said molten salt catalyst, feedstream, and product stream.

In one embodiment of the present invention, the wall thickness of asingle-layer reactor is between about 2 mm and about 30 mm. In anotherembodiment of the present invention, the wall thickness of asingle-layer reactor is between about 3 mm and about 20 mm. In yetanother embodiment of the present invention, the wall thickness of asingle-layer reactor is between about 4 mm and about 10 mm. In even yetanother embodiment of the present invention, the wall thickness of asingle-layer reactor is between about 5 mm and about 8 mm.

In one embodiment of the present invention, the stirred tank reactor isa bi-layer reactor. The bi-layer reactor comprises an inner surface,which is in contact with the molten salt catalyst, feed stream, andproduct stream, and is the innermost surface of the bi-layer reactor.The bi-layer reactor consists of an inner layer, which has an innerlayer thickness, an outer layer, which has an outer layer thickness, aninterface between the outer layer and the inner layer, and an outersurface, which is the outmost surface of the bi-layer reactor. Inanother embodiment of the present invention, the outer layer of thebi-layer reactor consists of two or more sublayers. In yet anotherembodiment of the present invention, the bi-layer reactor comprises anouter layer, an inner layer, an outer surface, an inner surface, and aninterface between said outer layer and said inner layer; wherein saidouter layer is made from an outer layer material, has an outer layerthickness, and extends from said interface to said outer surface;wherein said inner layer is made from an inner layer material, has aninner layer thickness, and extends from said inner surface to saidinterface; and wherein said inner surface is in contact with said moltensalt catalyst, feed stream, and product stream. In even yet anotherembodiment of the present invention, said outer layer comprises two ormore sublayers.

In one embodiment of the present invention, the inner layer thickness ofa bi-layer reactor is between about 1 mm and about 20 mm. In anotherembodiment of the present invention, the inner layer thickness of abi-layer reactor is between about 1.5 mm and about 10 mm. In yet anotherembodiment of the present invention, the inner layer thickness of abi-layer reactor is between about 2 mm and about 8 mm. In even yetanother embodiment of the present invention, the inner layer thicknessof a bi-layer reactor is between about 3 mm and about 6 mm. In oneembodiment of the present invention, the outer layer thickness of abi-layer reactor is between about 1 mm and about 20 mm. In anotherembodiment of the present invention, the outer layer thickness of abi-layer reactor is between about 1.5 mm and about 10 mm. In yet anotherembodiment of the present invention, the outer layer thickness of abi-layer reactor is between about 2 mm and about 8 mm. In even yetanother embodiment of the present invention, the outer layer thicknessof a bi-layer reactor is between about 3 mm and about 6 mm.

The molten salt catalysts, or the feed stream, or the product stream ofthe present invention can be corrosive to the reactors. Non-limitingexamples of materials that can be used in the present invention aseither wall materials or inner layer materials are glass; silica;sapphire; titanium; copper; silver; gold; tungsten; tantalum; zirconium;HASTELLOY® and HAYNES® alloys (Ni-based alloys; Haynes International,Inc.; Kokomo, Ind.); INCONEL®, INCOLOY®, and MONEL® alloys (Ni-basedalloys; Special Metals Corporation; Huntington, W. Va.); and plasticmaterials (e.g., polytetrafluoroethylene (PTFE), polyetherether ketone(PEEK), and polyether sulfone (PES)). In one embodiment of the presentinvention, the outer layer material is selected from the groupconsisting of stainless steel and carbon steel. In another embodiment ofthe present invention, the outer layer material is stainless steel andthe inner layer material of the bi-layer reactor is titanium.

In one embodiment of the present invention, the single-layer reactor hasa corrosion rate lower than about 1.3 mm/y. In another embodiment of thepresent invention, the bi-layer reactor has a corrosion rate lower thanabout 1.3 mm/y. For the purposes of the present invention, the corrosionrate is measured by weighing a wall material sample or an inner layermaterial sample before and after exposure to the reaction conditions, asthis is known to those skilled in the art.

In one embodiment of the present invention, said corrosion rate is lowerthan about 1 mm/y. In another embodiment of the present invention, saidcorrosion rate is lower than about 0.5 mm/y. In yet another embodimentof the present invention, said corrosion rate is lower than about 0.13mm/y. In even yet another embodiment of the present invention, saidcorrosion rate is lower than about 0.05 mm/y.

In one embodiment of the present invention, the temperature during saiddehydration is greater than about 50° C. In another embodiment of thepresent invention, the temperature during said dehydration is betweenabout 80° C. and about 400° C. In yet another embodiment of the presentinvention, the temperature during said dehydration is between about 140°C. and about 300° C. In even yet another embodiment of the presentinvention, the temperature during said dehydration is between about 150°C. and about 280° C. In one embodiment of the present invention, thetemperature during said dehydration is between about 180° C. and about250° C. In another embodiment of the present invention, the temperatureduring said dehydration is about 220° C. In yet another embodiment ofthe present invention, the temperature during said dehydration is about150° C. In even yet another embodiment of the present invention, thetemperature during said dehydration is about 160° C. In one embodimentof the present invention, the temperature during said dehydration isabout 180° C.

The contacting of the feed stream and the molten salt catalyst can beperformed under vacuum, at atmospheric pressure, or at pressure higherthan atmospheric. In one embodiment of the present invention, thecontacting is performed under a total pressure of at least about 1 bar.In another embodiment of the present invention, the contacting isperformed under a total pressure between about 250 mbar and about 2 bar.In yet another embodiment of the present invention, the contacting isperformed at atmospheric pressure.

In one embodiment of the present invention, said WHSV is between about0.02 h⁻¹ and about 10 h⁻¹. In another embodiment of the presentinvention, said WHSV is between about 0.2 h⁻¹ and about 2 h⁻¹. In yetanother embodiment of the present invention, said WHSV is between about0.3 h⁻¹ and about 1.4 h⁻¹. In even yet another embodiment of the presentinvention, said WHSV is between about 0.3 h⁻¹ and about 0.4 h⁻¹. In oneembodiment of the present invention, said WHSV is about 0.4 h⁻¹.

In one embodiment of the present invention, said acrylic acid, acrylicacid derivatives, or mixtures thereof are produced with a yield of atleast 10 mol %. In another embodiment of the present invention, saidacrylic acid, acrylic acid derivatives, or mixtures thereof are producedwith a yield of at least about 20%. In yet another embodiment of thepresent invention, said acrylic acid, acrylic acid derivatives, ormixtures thereof are produced with a yield of at least about 30 mol %.In even yet another embodiment of the present invention, said acrylicacid, acrylic acid derivatives, or mixtures thereof are produced with ayield of at least 40 mol %. In one embodiment of the present invention,said acrylic acid, acrylic acid derivatives, or mixtures thereof areproduced with a yield of at least about 60%. In another embodiment ofthe present invention, said acrylic acid, acrylic acid derivatives, ormixtures thereof are produced with a yield of at least about 80 mol %.

In one embodiment of the present invention, said acrylic acid, acrylicacid derivatives, or mixtures thereof are produced with a selectivity ofat least about 50 mol %. In another embodiment of the present invention,said acrylic acid, acrylic acid derivatives, or mixtures thereof areproduced with a selectivity of at least about 70 mol %. In yet anotherembodiment of the present invention, said acrylic acid, acrylic acidderivatives, or mixtures thereof are produced with a selectivity of atleast about 80 mol %.

In one embodiment of the present invention, said acrylic acid, acrylicacid derivatives, or mixtures thereof are produced with a yield of atleast about 10 mol % and with a selectivity of at least about 50 mol %.In another embodiment of the present invention, said acrylic acid,acrylic acid derivatives, or mixtures thereof are produced with a yieldof at least about 30 mol % and with a selectivity of at least about 70mol %. In yet another embodiment of the present invention, said acrylicacid, acrylic acid derivatives, or mixtures thereof are produced with ayield of at least about 50 mol % and with a selectivity of at leastabout 80 mol %. In even yet another embodiment of the present invention,said acrylic acid, acrylic acid derivatives, or mixtures thereof areproduced with a yield of at least about 80 mol % and with a selectivityof at least about 80 mol %.

In one embodiment of the present invention, propionic acid is producedas an impurity along with said acrylic acid, acrylic acid derivatives,or mixtures thereof; and wherein the selectivity of said propionic acidis less than about 5 mol %. In another embodiment of the presentinvention, propionic acid is produced as an impurity along with saidacrylic acid, acrylic acid derivatives, or mixtures thereof; and whereinthe selectivity of said propionic acid is less than about 1 mol %.

In one embodiment of the present invention, said acrylic acid, acrylicacid derivatives, or mixtures thereof are produced with a yield of atleast about 10 mol % and with a selectivity of at least about 50 mol %over a TOS of about 72 h; wherein propionic acid is produced as animpurity along with said acrylic acid, acrylic acid derivatives, ormixtures thereof; and wherein the selectivity of said propionic acid isless than about 5 mol % over said TOS of about 72 h. In anotherembodiment of the present invention, said acrylic acid, acrylic acidderivatives, or mixtures thereof are produced with a yield of at leastabout 30 mol % and with a selectivity of at least about 70 mol % over aTOS of about 72 h; wherein propionic acid is produced as an impurityalong with said acrylic acid, acrylic acid derivatives, or mixturesthereof; and wherein the selectivity of said propionic acid is less thanabout 1 mol % over said TOS of about 72 h.

In one embodiment of the present invention, said acrylic acid, acrylicacid derivatives, or mixtures thereof are produced with a conversion ofsaid hydroxypropionic acid, hydroxypropionic acid derivatives, ormixtures thereof of more than about 50 mol %. In another embodiment ofthe present invention, said acrylic acid, acrylic acid derivatives, ormixtures thereof are produced with a conversion of said hydroxypropionicacid, hydroxypropionic acid derivatives, or mixtures thereof of morethan about 80 mol %. In yet another embodiment of the present invention,said acrylic acid, acrylic acid derivatives, or mixtures thereof areproduced with a conversion of said hydroxypropionic acid,hydroxypropionic acid derivatives, or mixtures thereof of more thanabout 90 mol %.

In one embodiment of the present invention, acetic acid, pyruvic acid,1,2-propanediol, hydroxyacetone, acrylic acid dimer, and2,3-pentanedione are produced along with said acrylic acid, acrylic acidderivatives, or mixtures thereof with a yield of less than about 2 mol %each. In another embodiment of the present invention, acetic acid,pyruvic acid, 1,2-propanediol, hydroxyacetone, acrylic acid dimer, and2,3-pentanedione are produced along with said acrylic acid, acrylic acidderivatives, or mixtures thereof with a yield of less than about 0.5 mol% each. In yet another embodiment of the present invention, acetaldehydeis produced along with said acrylic acid, acrylic acid derivatives, ormixtures thereof with a yield of less than about 8 mol %. In even yetanother embodiment of the present invention, acetaldehyde is producedalong with said acrylic acid, acrylic acid derivatives, or mixturesthereof with a yield of less than about 4 mol %. In one embodiment ofthe present invention, acetaldehyde is produced along with said acrylicacid, acrylic acid derivatives, or mixtures thereof with a yield of lessthan about 3 mol %.

The feed stream can be introduced into the reactor with a simple tube orthrough atomization nozzles. Non-limiting examples of atomizationnozzles comprise fan nozzles, pressure swirl atomizers, air blastatomizers, two-fluid atomizers, rotary atomizers, and supercriticalcarbon dioxide atomizers. In one embodiment of the present invention,the droplets of the feed stream are less than about 2 mm in diameter. Inanother embodiment of the present invention, the droplets of the feedstream are less than about 500 μm in diameter. In yet another embodimentof the present invention, the droplets of the feed stream are less thanabout 200 μm in diameter. In even yet another embodiment of the presentinvention, the droplets of the feed stream are less than about 100 μm indiameter.

The product stream can be delivered out of the molten salt catalyst viaa variety of methods. Non-limiting examples of methods of delivering theproduct stream out of the molten salt catalyst are evaporation,dilution, vacuum distillation, steam distillation, and gas stripping.Inert gases or carrier gases can be used in gas stripping. Non-limitingexamples as strip gases are air, nitrogen, argon, carbon monoxide,carbon dioxide, and acetaldehyde. In one embodiment of the presentinvention, said contacting proceeds in the presence of a strip gas. Inanother embodiment of the present invention, said strip gas is selectedfrom the group consisting of air, nitrogen, argon, carbon monoxide, andmixtures thereof.

The product stream produced in said dehydration is cooled to give aliquid acrylic acid stream as the product stream. The time required tocool the acrylic acid stream must be controlled to reduce acrylic acidpolymerization. In one embodiment of the present invention, theresidence time of the product stream in the cooling step is less thanabout 30 s. In another embodiment of the present invention, theresidence time of the product stream in the cooling step is betweenabout 0.1 s and about 60 s.

The product stream comprising acrylic acid, acrylic acid derivatives, ormixtures thereof produced according to the present invention can bepurified using some or all of the processes of extraction, drying,distilling, cooling, partial melting, and decanting described inUS20130274518A1 (incorporated herein by reference) to produce crude andglacial acrylic acid. After purification, the crude and glacial acrylicacid can be polymerized to produce a superabsorbent polymer usingprocesses that are similar to those described in US20130274697A1(incorporated herein by reference).

In one embodiment of the present invention, a method of making acrylicacid, acrylic acid derivatives, or mixtures thereof comprises contactinga feed stream comprising lactic acid, lactic acid derivatives, ormixtures thereof with a molten salt catalyst in a reactor at atemperature; wherein said molten salt catalyst comprises an IL and anacid; and whereby acrylic acid, acrylic acid derivatives, or mixturesthereof are produced as a result of said dehydration in said reactor. Inanother embodiment of the present invention, the lactic acid derivativeis 2-APA; the IL is [PBu₄]Br and the acid is H₄P₂O₇; the molar ratio ofthe IL to the acid is about 4.75; the temperature is about 220° C.; andthe acrylic acid is produced with a yield of at least about 10 mol %. Inyet another embodiment of the present invention, the lactic acidderivative is lactide; the IL is [PBu₄]Br and the acid is H₄P₂O₇; themolar ratio of said IL to said acid is about 4.75; the temperature isabout 220° C.; and the acrylic acid is produced with a yield of at leastabout 10 mol %.

In one embodiment of the present invention, a method of making acrylicacid comprises contacting a feed stream comprising 2-APA with a moltensalt catalyst in a reactor at 220° C., the molten salt catalystcomprises [PBu₄]Br and H₄P₂O₇ at a molar ratio of about 4.75, thecontacting proceeds under atmospheric pressure and in the presence of astrip gas; the strip gas is argon, and the acrylic acid is produced as aresult of the contacting in the reactor with a yield of at least about30 mol %.

In another embodiment of the present invention, a method of makingacrylic acid comprises contacting a feed stream comprising 2-APA with amolten salt catalyst in a reactor at 220° C., the molten salt catalystcomprises [PBu₄]Br and HBr at a molar ratio of about 4.75, thecontacting proceeds under atmospheric pressure, and the acrylic acid isproduced as a result of the contacting in the reactor with a yield of atleast about 18 mol %.

In yet another embodiment of the present invention, a method for makingacrylic acid, comprises contacting a feed stream comprising 2-APA with amolten salt catalyst in a reactor at 220° C., the molten salt catalystcomprises ethyltriphenylphosphonium bromide ([EtPPh₃]Br) and HBr at amolar ratio of about 4, the contacting proceeds under atmosphericpressure, and the acrylic acid is produced as a result of the contactingin the reactor with a yield of at least about 25 mol %.

In even yet another embodiment of the present invention, a method formaking acrylic acid, comprises contacting a feed stream comprisinglactide with a molten salt catalyst in a reactor at 150° C., the moltensalt catalyst comprises tetrabutylphosphonum bromide ([PBu₄]Br) and2-bromopropionic acid (2-BrPA) at a molar ratio of about 10, thecontacting proceeds under atmospheric pressure, and the acrylic acid isproduced as a result of the contacting in the reactor with a yield of atleast about 47 mol %.

In one embodiment of the present invention, a method for making acrylicacid, comprises contacting a feed stream comprising lactide with amolten salt catalyst in a reactor at 150° C., the molten salt catalystcomprises tetrabutylphosphonum bromide ([PBu₄]Br) and 2-bromopropionicacid (2-BrPA) at a molar ratio of about 20, the contacting proceedsunder atmospheric pressure, and the acrylic acid is produced as a resultof the contacting in the reactor with a yield of at least about 52 mol%.

In one embodiment of the present invention, the method of making acrylicacid, acrylic acid derivatives, or mixtures thereof is a one-stepprocess; wherein the feed stream to the one-step process is lactic acid,lactic acid derivaties, or mixtures thereof; and wherein the outputstream from the one-step process is acrylic acid, acrylic acidderivatives, or mixtures thereof. In another embodiment of the presentinvention, the feed stream to the one-step process is lactide and theoutput stream from the one-step process is acrylic acid.

In yet another embodiment of the present invention, the method of makingacrylic acid, acrylic acid derivatives, or mixtures thereof is atwo-step process; wherein the feed stream to the first step of thetwo-step process is lactic acid, lactic acid derivaties, or mixturesthereof; wherein the output stream from the first step and the feedstream to the second step of the two-step process is 2-bromopropionicacid (2-BrPA); and wherein the output stream from the second step of thetwo-step process is acrylic acid, acrylic acid derivatives, or mixturesthereof. In even yet another embodiment of the present invention, thefeed stream to the first step of the two-step process is lactide, andthe output stream from the second step of the two-step process isacrylic acid.

In one embodiment of the present invention, the method of making acrylicacid is a two-step process; wherein the feed stream to the first step ofthe two-step process is lactide; wherein said first step comprisescontacting said lactide with 3-methyl-1-(4-butane sulfonic acid)imidazolium bromide ([MIMBS]Br) for about 5 h at a temperature of about120° C. and atmospheric pressure; whereby 2-bromopropionic acid (2-BrPA)is produced at a yield of more than about 60 mol % and selectivity ofmore than about 95 mol %; wherein said 2-BrPA is fed into the secondstep; wherein said second step comprises contacting said 2-BrPA with[PBu₄]Br for about 3 h at a temperature of about 160° C. and atmosphericpressure; and whereby acrylic acid is produced at a yield of more thanabout 45 mol % and selectivity of more than about 85 mol %.

In another embodiment of the present invention, the method of makingacrylic acid, acrylic acid derivatives, or mixtures thereof is athree-step process; wherein the feed stream to the first step of thethree-step process is lactic acid, lactic acid derivaties, or mixturesthereof; wherein the output stream from the first step and the feedstream to the second step of the three-step process is 2-bromopropionicacid (2-BrPA); wherein the output stream from the second step and thefeed stream to the third step of the three-step process is3-bromopropionic acid (3-BrPA); and wherein the output stream from thethird step of the three-step process is acrylic acid, acrylic acidderivatives, or mixtures thereof. In yet another embodiment of thepresent invention, the feed stream to the first step of the three-stepprocess is lactide, and the output stream from the third step of thethree-step process is acrylic acid.

In even yet another embodiment of the present invention, the method ofmaking acrylic acid is a three-step process; wherein the feed stream tothe first step of the three-step process is lactide; wherein said firststep comprises contacting said lactide with 3-methyl-1-(4-butanesulfonic acid) imidazolium bromide ([MIMBS]Br) for about 5 h at atemperature of about 120° C. and atmospheric pressure; whereby2-bromopropionic acid (2-BrPA) is produced at a yield of more than about60 mol % and selectivity of more than about 95 mol %; wherein said2-BrPA is fed into the second step; wherein said second step comprisescontacting said 2-BrPA with [PBu₄]Br for about 20 h at a temperature ofabout 160° C. and atmospheric pressure; whereby 3-bromopropionic acid(3-BrPA) is produced at a yield of more than about 80 mol % andselectivity of more than about 90 mol %; wherein said 3-BrPA is fed intothe third step; wherein said third step comprises contacting said 3-BrPAwith trioctylamine (TOA) for about 30 min at a temperature of about 180°C. and atmospheric pressure; and whereby acrylic acid is produced at ayield of more than about 90 mol % and selectivity of more than about 90mol %.

In one embodiment of the present invention, the feed stream compriseslactide. In another embodiment of the present invention, the molten saltcatalyst comprises [PBu₄]Br and 2-BrPA. In yet another embodiment of thepresent invention, the temperature in the reactor is between about 110°C. and about 240° C. In even yet another embodiment of the presentinvention, the temperature in the reactor is between about 130° C. andabout 230° C. In one embodiment of the present invention, thetemperature in the reactor is between about 150° C. and about 220° C. Inanother embodiment of the present invention, the temperature in thereactor is between about 160° C. and about 190° C. In yet anotherembodiment of the present invention, the temperature in the reactor isabout 150° C. In even yet another embodiment of the present invention,the temperature in the reactor is about 170° C.

In one embodiment of the present invention, the residence time of thefeed stream in the reactor is between about 5 min and about 10 days. Inanother embodiment of the present invention, the residence time of thefeed stream in the reactor is between about 15 min and about 7 days (168h). In yet another embodiment of the present invention, the residencetime of the feed stream in the reactor is between about 30 min and about3 days (72 h). In even yet another embodiment of the present invention,the residence time of the feed stream in the reactor is between about 1h and about 2 days (48 h). In one embodiment of the present invention,the residence time of the feed stream in the reactor is between about 2h and about 1 day (24 h). In another embodiment of the presentinvention, the residence time of the feed stream in the reactor is about0.33 h. In yet another embodiment of the present invention, theresidence time of the feed stream in the reactor is about 2 h. In evenyet another embodiment of the present invention, the residence time ofthe feed stream in the reactor is about 7 h.

In one embodiment of the present invention, the molar ratio of thelactic acid equivalent (LAe) to [PBu₄]Br to 2-BrPA is between about1:0.2:0.1 and about 1:5:0.1. In another embodiment of the presentinvention, the molar ratio of the lactic acid equivalent (LAe) to[PBu₄]Br to 2-BrPA is between about 1:0.5:0.1 and about 1:2:0.1. In oneembodiment of the present invention, the molar ratio of the lactic acidequivalent (LAe) to [PBu₄]Br to 2-BrPA is about 1:1:0.1. In yet anotherembodiment of the present invention, the molar ratio of the lactic acidequivalent (LAe) to [PBu₄]Br to 2-BrPA is about 1:2:0.1.

In one embodiment of the present invention, the molar ratio of thelactic acid equivalent (LAe) to [PBu₄]Br is between about 1:0.25 andabout 1:4. In another embodiment of the present invention, the molarratio of the lactic acid equivalent (LAe) to [PBu₄]Br is between about1:0.33 and about 1:3. In yet another embodiment of the presentinvention, the molar ratio of the lactic acid equivalent (LAe) to[PBu₄]Br is between about 1:0.5 and about 1:2. In even yet anotherembodiment of the present invention, the molar ratio of the lactic acidequivalent (LAe) to [PBu₄]Br is about 1:1. In one embodiment of thepresent invention, the molar ratio of the lactic acid equivalent (LAe)to [PBu₄]Br is about 1:2.

In one embodiment of the present invention, the acrylic acid produced inthe reactor is removed from the reactor as it is produced. In anotherembodiment of the present invention, the acrylic acid is removed fromthe reactor via distillation. In yet another embodiment of the presentinvention, the acrylic acid is removed with the use of a strip gas.

In one embodiment of the present invention, the water is removed fromthe reactor as it is introduced into the reactor or produced in thereactor. In another embodiment of the present invention, the water isremoved from the reactor via distillation. In yet another embodiment ofthe present invention, the water is removed with the use of a strip gas.

In one embodiment of the present invention, the feed stream compriseslactic acid and water, and the water is removed from the reactor. Inanother embodiment of the present invention, the feed stream compriseslactic acid oligomers. In yet another embodiment of the presentinvention, the feed stream comprises lactic acid and water, and thelactic acid oligomers are formed in the reactor. In even yet anotherembodiment of the present invention, the feed stream comprises lacticacid and water, and the lactic acid oligomers and acrylic acid areproduced simultaneously in the reactor. In one embodiment of the presentinvention, the feed stream comprises lactic acid and water, the lacticacid oligomers and acrylic acid are produced simultaneously in thereactor, and the water produced is removed from the reactorsimultaneously with the production of the lactic acid oligomers andacrylic acid.

In another embodiment of the present invention, the feed streamcomprises lactic acid and water, and the lactide and acrylic acid areproduced simultaneously in the reactor. In yet another embodiment of thepresent invention, the feed stream comprises lactic acid and water, thelactide and acrylic acid are produced simultaneously in the reactor, andthe water produced is removed from the reactor simultaneously with theproduction of the lactide and acrylic acid. In even yet anotherembodiment of the present invention, the feed stream comprises lacticacid and water, the lactide and acrylic acid are produced simultaneouslyin the reactor, and the acrylic acid and water produced are removed fromthe reactor simultaneously with the production of the lactide.

In one embodiment of the present invention, the feed stream compriseslactide, the molten salt catalyst comprises [PBu₄]Br and 2-BrPA, themolar ratio of lactic acid equivalent to [PBu₄]Br to 2-BrPA is about1:2:01, the reaction temperature is about 160° C., the reaction time isabout 24 h, and acrylic acid is produced at a yield of about 58 mol %.In another embodiment of the present invention, the feed streamcomprises lactide, the molten salt catalyst comprises [PBu₄]Br and2-BrPA, the molar ratio of lactic acid equivalent to [PBu₄]Br to 2-BrPAis about 1:2:01, the reaction temperature is about 160° C., the reactiontime is about 24 h, the acrylic acid produced is removed from thereactor as it is produced, and acrylic acid is produced at a yieldexceeding about 58 mol %. In yet another embodiment of the presentinvention, the feed stream comprises lactide, the molten salt catalystcomprises [PBu₄]Br and 2-BrPA, the molar ratio of lactic acid equivalentto [PBu₄]Br to 2-BrPA is about 1:2:01, the reaction temperature is about160° C., the reaction time is about 24 h, the acrylic acid produced isremoved from the reactor as it is produced, and acrylic acid is producedat a yield exceeding about 70 mol %. In even yet another embodiment ofthe present invention, the feed stream comprises lactide, the moltensalt catalyst comprises [PBu₄]Br and 2-BrPA, the molar ratio of lacticacid equivalent to [PBu₄]Br to 2-BrPA is about 1:2:01, the reactiontemperature is about 160° C., the reaction time is about 24 h, theacrylic acid produced is removed from the reactor as it is produced, andacrylic acid is produced at a yield exceeding about 80 mol %.

In one embodiment of the present invention, the molten salt catalystcomprises [PBu₄]Br and 2-BrPA, the molar ratio of lactic acid equivalentto [PBu₄]Br to 2-BrPA is about 1:2:01, the reaction temperature is about170° C., the reaction time is about 7 h, and acrylic acid is produced ata yield of about 56 mol %. In another embodiment of the presentinvention, the molten salt catalyst comprises [PBu₄]Br and 2-BrPA, themolar ratio of lactic acid equivalent to [PBu₄]Br to 2-BrPA is about1:2:01, the reaction temperature is about 170° C., the reaction time isabout 7 h, the acrylic acid produced is removed from the reactor as itis produced, and acrylic acid is produced at a yield exceeding about 56mol %. In yet another embodiment of the present invention, the moltensalt catalyst comprises [PBu₄]Br and 2-BrPA, the molar ratio of lacticacid equivalent to [PBu₄]Br to 2-BrPA is about 1:2:01, the reactiontemperature is about 170° C., the reaction time is about 7 h, theacrylic acid produced is removed from the reactor as it is produced, andacrylic acid is produced at a yield exceeding about 70 mol %. In evenyet another embodiment of the present invention, the molten saltcatalyst comprises [PBu₄]Br and 2-BrPA, the molar ratio of lactic acidequivalent to [PBu₄]Br to 2-BrPA is about 1:2:01, the reactiontemperature is about 170° C., the reaction time is about 7 h, theacrylic acid produced is removed from the reactor as it is produced, andacrylic acid is produced at a yield exceeding about 80 mol %.

In one embodiment of the present invention, the molten salt catalystcomprises [PBu₄]Br and 2-BrPA, the molar ratio of lactic acid equivalentto [PBu₄]Br to 2-BrPA is about 1:2:01, the reaction temperature is about190° C., the reaction time is about 2 h, and acrylic acid is produced ata yield of about 54 mol %. In another embodiment of the presentinvention, the molten salt catalyst comprises [PBu₄]Br and 2-BrPA, themolar ratio of lactic acid equivalent to [PBu₄]Br to 2-BrPA is about1:2:01, the reaction temperature is about 190° C., the reaction time isabout 2 h, the acrylic acid produced is removed from the reactor as itis produced, and acrylic acid is produced at a yield exceeding about 54mol %. In yet another embodiment of the present invention, the moltensalt catalyst comprises [PBu₄]Br and 2-BrPA, the molar ratio of lacticacid equivalent to [PBu₄]Br to 2-BrPA is about 1:2:01, the reactiontemperature is about 190° C., the reaction time is about 2 h, theacrylic acid produced is removed from the reactor as it is produced, andacrylic acid is produced at a yield exceeding about 70 mol %. In evenyet another embodiment of the present invention, the molten saltcatalyst comprises [PBu₄]Br and 2-BrPA, the molar ratio of lactic acidequivalent to [PBu₄]Br to 2-BrPA is about 1:2:01, the reactiontemperature is about 190° C., the reaction time is about 2 h, theacrylic acid produced is removed from the reactor as it is produced, andacrylic acid is produced at a yield exceeding about 80 mol %.

In one embodiment of the present invention, the molten salt catalystcomprises [PBu₄]Br and 2-BrPA, the molar ratio of lactic acid equivalentto [PBu₄]Br to 2-BrPA is about 1:2:01, the reaction temperature is about220° C., the reaction time is about 0.33 h, and acrylic acid is producedat a yield of about 50 mol %. In another embodiment of the presentinvention, the molten salt catalyst comprises [PBu₄]Br and 2-BrPA, themolar ratio of lactic acid equivalent to [PBu₄]Br to 2-BrPA is about1:2:01, the reaction temperature is about 220° C., the reaction time isabout 0.33 h, the acrylic acid produced is removed from the reactor asit is produced, and acrylic acid is produced at a yield exceeding about50 mol %. In yet another embodiment of the present invention, the moltensalt catalyst comprises [PBu₄]Br and 2-BrPA, the molar ratio of lacticacid equivalent to [PBu₄]Br to 2-BrPA is about 1:2:01, the reactiontemperature is about 220° C., the reaction time is about 0.33 h, theacrylic acid produced is removed from the reactor as it is produced, andacrylic acid is produced at a yield exceeding about 70 mol %. In evenyet another embodiment of the present invention, the molten saltcatalyst comprises [PBu₄]Br and 2-BrPA, the molar ratio of lactic acidequivalent to [PBu₄]Br to 2-BrPA is about 1:2:01, the reactiontemperature is about 220° C., the reaction time is about 0.33 h, theacrylic acid produced is removed from the reactor as it is produced, andacrylic acid is produced at a yield exceeding about 80 mol %.

IV Examples

The following examples are provided to illustrate the invention, but arenot intended to limit the scope thereof.

Example 1—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br Ionic Liquid,Molar Ratio of Lactic Acid Equivalent (LAe) to [PBu₄]Br Equal to 2.57:1,Temperature 220° C., and No Strip Gas

18 g of solid tetrabutylphosphonium bromide salt catalyst ([PBu₄]Br;51.99 mmol, 98%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany;catalog #189138) were placed in a 100 mL three-necked glass reactor atroom temperature and atmospheric conditions, and then heated to 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed using a water-cooledcondenser. The liquid products were collected in an ice-cooled flask,and the gaseous by-products were routed to the off-gas. After an overallprocess time of 150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #M7200) wasadded to the distillation flask as internal standard and the collecteddistillate, as well as the molten salt catalyst, were both analyzed viaoff-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of the distillategave an acrylic acid yield of about 1.3 mol % and a 2-APA conversion of≥97 mol %.

Example 2—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and H₄P₂O₇Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to H₄P₂O₇ Equal to 71.8:28:1, Temperature 220° C., and No StripGas

The molten salt catalyst with a molar ratio of 28 was prepared by firstmixing 0.37 g of solid pyrophosphoric acid (H₄P₂O₇; 1.86 mmol, ≥90%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #83210) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 5.5 mol % and a 2-APA conversion of ≥97 mol %.

Example 3—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and H₄P₂O₇Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to H₄P₂O₇ Equal to 36:14:1, Temperature 220° C., and No StripGas

The molten salt catalyst with a molar ratio of 14 was prepared by firstmixing 0.73 g of solid pyrophosphoric acid (H₄P₂O₇; 3.71 mmol, ≥90%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #83210) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 7.0 mol % and a 2-APA conversion of ≥97 mol %.

Example 4—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and H₄P₂O₇Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to H₄P₂O₇ Equal to 18:7:1, Temperature 220° C., and No StripGas

The molten salt catalyst with a molar ratio of 7 was prepared by firstmixing 1.47 g of solid pyrophosphoric acid (H₄P₂O₇; 7.43 mmol, ≥90%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #83210) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 9.6 mol % and a 2-APA conversion of ≥97 mol %.

Example 5—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and H₄P₂O₇Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to H₄P₂O₇ Equal to 12.2:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 2.16 g of solid pyrophosphoric acid (H₄P₂O₇; 10.94 mmol,≥90%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #83210)and 18 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol,98%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138)at room temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 11.1 mol % and a 2-APA conversion of ≥97 mol %.

Example 6—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and H₄P₂O₇Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to H₄P₂O₇ Equal to 9:3.5:1, Temperature 220° C., and No StripGas

The molten salt catalyst with a molar ratio of 3.5 was prepared by firstmixing 2.94 g of solid pyrophosphoric acid (H₄P₂O₇; 14.85 mmol, ≥90%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #83210) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 8.8 mol % and a 2-APA conversion of ≥97 mol %.

Example 7—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and H₄P₂O₇Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to H₄P₂O₇ Equal to 2.57:1:1, Temperature 220° C., and No StripGas

The molten salt catalyst with a molar ratio of 1 was prepared by firstmixing 10.28 g of solid pyrophosphoric acid (H₄P₂O₇; 51.99 mmol, ≥90%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #83210) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 1.4 mol % and a 2-APA conversion of ≥97 mol %.

Example 8—Acrylic Acid Synthesis from 2-APA with H₄P₂O₇ Acid, MolarRatio of Lactic Acid Equivalent (LAe) to H₄P₂O₇ Equal to 1.47:1,Temperature 220° C., and No Strip Gas

18 g of solid pyrophosphoric acid catalyst (H₄P₂O₇; 91.02 mmol, ≥90%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #83210) wereplaced in a 100 mL three-necked glass reactor at room temperature andatmospheric conditions, and then heated to 220° C. under continuousstirring with an overhead stirrer at a speed of 300 rpm. After thecatalyst reached 220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APAwere fed into the glass reactor at a constant feeding rate of 0.5 mL/minby means of a funnel. Uncontrollable foaming was observed in the glassreactor that yielded in no distillate and thus the yield of acrylic acidwas 0 mol %.

Example 9—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and KBr MoltenSalt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to [PBu₄]Brto KBr Equal to 12.2:4.75:1, Temperature 220° C., and No Strip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 1.32 g of solid potassium bromide (KBr; 10.94 mmol, 99%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #P0838) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 0.7 mol %.

Example 10—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and CaBr₂Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to CaBr₂ Equal to 12.2:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 2.23 g of solid calcium bromide (CaBr₂; 10.94 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #233749) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 11.8 mol % and a 2-APA conversion of ≥97 mol %.

Example 11—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and MgBr₂Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to MgBr₂ Equal to 12.2:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 2.06 g of solid magnesium bromide (MgBr₂; 10.94 mmol, ≥98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #360074) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 12.9 mol % and a 2-APA conversion of ≥97 mol %.

Example 12—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and AlBr₃Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to AlBr₃ Equal to 12.2:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 2.98 g of solid aluminum tribromide (AlBr₃; 10.94 mmol,≥98%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #210072)and 18 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol,98%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138)at room temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 14.3 mol % and a 2-APA conversion of ≥94 mol %.

Example 13—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and InBr₃Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to InBr₃ Equal to 12.2:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 3.92 g of solid indium tribromide (InBr₃; 10.94 mmol, ≥99%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #308285) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 0.8 mol % and a 2-APA conversion of ≥97 mol %.

Example 14—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and NiBr₂Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to NiBr₂ Equal to 12.2:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 2.44 g of solid Nickel dibromide (NiBr₂; 10.94 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #217891) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 0.5 mol %.

Example 15—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and CoBr₂Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to CoBr₂ Equal to 12.2:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 2.42 g of solid cobalt dibromide (CoBr₂; 10.94 mmol, 99%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #334022) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 0.6 mol %.

Example 16—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and ZnBr₂Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to ZnBr₂ Equal to 12.2:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 2.47 g of solid zinc dibromide (ZnBr₂; 10.94 mmol, 99.999%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #230022) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 0.7 mol %.

Example 17—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and FeBr₃Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to FeBr₃ Equal to 12.2:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 3.30 g of solid iron tribromide (FeBr₃; 10.94 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #217883) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 1.0 mol %.

Example 18—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and GaBr₃Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to GaBr₃ Equal to 14.95:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 2.76 g of solid gallium tribromide (GaBr₃; 8.93 mmol,99.999%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog#381357) and 14.69 g of solid tetrabutylphosphonium bromide ([PBu₄]Br;42.43 mmol, 98%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany;catalog #189138) at room temperature and atmospheric conditions in a 100mL three-necked glass reactor, and then heating the catalyst at atemperature of 220° C. under continuous stirring with an overheadstirrer at a speed of 300 rpm. After the molten salt catalyst reached aconstant temperature of 220° C., 17.64 g (133.5 mmol) of synthesizedpure 2-APA were fed into the glass reactor at a constant feeding rate of0.5 mL/min by means of a funnel. The 2-APA was slowly dropped into theglass reactor and the reaction products were semi-batchwise removed. Theliquid products were condensed and collected in an ice-cooled flask, andthe gaseous by-products were routed to the off-gas. After an overallprocess time of 150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #M7200) wasadded to the distillation flask as internal standard and the collecteddistillate, as well as the molten salt catalyst, were both analyzed viaoff-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of the distillategave an acrylic acid yield of about 1.2 mol %.

Example 19—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and CuBr₂Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to CuBr₂ Equal to 12.2:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 2.47 g of solid copper dibromide (CuBr₂; 10.94 mmol, 99%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #221775) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 8.2 mol % and a 2-APA conversion of ≥90 mol %.

Example 20—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and HBr/AlBr₃Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to HBr/AlBr₃ Equal to 12.2:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 2.98 g of solid aluminum tribromide (AlBr₃; 10.94 mmol,≥98%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #210072),1.88 g of liquid hydrobromic acid (HBr; 10.94 mmol, 47%; Merck KGaA,Darmstadt, Germany; catalog #1.00304.0500) and 18 g of solidtetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #189138) at room temperatureand atmospheric conditions in a 100 mL three-necked glass reactor, andthen heating the catalyst at a temperature of 220° C. under continuousstirring with an overhead stirrer at a speed of 300 rpm. After themolten salt catalyst reached a constant temperature of 220° C., 17.64 g(133.5 mmol) of synthesized pure 2-APA were fed into the glass reactorat a constant feeding rate of 0.5 mL/min by means of a funnel. The 2-APAwas slowly dropped into the glass reactor and the reaction products weresemi-batchwise removed. The liquid products were condensed and collectedin an ice-cooled flask, and the gaseous by-products were routed to theoff-gas. After an overall process time of 150 min, 1 g of mesitylene(C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #M7200) was added to the distillation flask as internalstandard and the collected distillate, as well as the molten saltcatalyst, were both analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹HqNMR analysis of the distillate gave an acrylic acid yield of about 9.9mol % and a 2-APA conversion of ≥93 mol %.

Example 21—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and AceticAcid (CH₃CO₂H) Molten Salt Catalyst, Molar Ratio of Lactic AcidEquivalent (LAe) to [PBu₄]Br to Acetic Acid Equal to 12.2:4.75:1,Temperature 220° C., and No Strip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 0.67 g of liquid acetic acid (acetic acid; 11.16 mmol,100%; Merck Schuchardt OHG, Hohenbrunn, Germany; catalog #100063) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 99%;Alfa Aesar, Karlsruhe, Germany; catalog #A10868) at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor, and thenheating the catalyst at a temperature of 220° C. under continuousstirring with an overhead stirrer at a speed of 300 rpm. After themolten salt catalyst reached a constant temperature of 220° C., 17.64 g(133.5 mmol) of synthesized pure 2-APA were fed into the glass reactorat a constant feeding rate of 0.5 mL/min by means of a hose pump. The2-APA was slowly dropped into the glass reactor and the reactionproducts were semi-batchwise removed. The liquid products were condensedand collected in an ice-cooled flask, and the gaseous by-products wererouted to the off-gas. After an overall process time of 150 min, 1 g ofmesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-Aldrich Chemie GmbH,Taufkirchen, Germany; catalog #M7200) was added to the distillationflask as internal standard and the collected distillate, as well as themolten salt catalyst, were both analyzed via off-line ¹H NMR (JEOL ECX400 MHz). ¹H qNMR analysis of the distillate gave an acrylic acid yieldof about 3.4 mol % and a 2-APA conversion of ≥97 mol %.

Example 22—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and H₃PO₄Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to H₃PO₄ Equal to 12.2:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 1.26 g of liquid phosphoric acid (H₃PO₄; 10.94 mmol, 85%;Merck KGaA, Darmstadt, Germany; catalog #1.00573.1000) and 18 g of solidtetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #189138) at room temperatureand atmospheric conditions in a 100 mL three-necked glass reactor, andthen heating the catalyst at a temperature of 220° C. under continuousstirring with an overhead stirrer at a speed of 300 rpm. After themolten salt catalyst reached a constant temperature of 220° C., 17.64 g(133.5 mmol) of synthesized pure 2-APA were fed into the glass reactorat a constant feeding rate of 0.5 mL/min by means of a funnel. The 2-APAwas slowly dropped into the glass reactor and the reaction products weresemi-batchwise removed. The liquid products were condensed and collectedin an ice-cooled flask, and the gaseous by-products were routed to theoff-gas. After an overall process time of 150 min, 1 g of mesitylene(C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #M7200) was added to the distillation flask as internalstandard and the collected distillate, as well as the molten saltcatalyst, were both analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹HqNMR analysis of the distillate gave an acrylic acid yield of about 6.2mol % and a 2-APA conversion of ≥97 mol %.

Example 23—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and H₂SO₄Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to H₂SO₄ Equal to 12.2:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 2.15 g of liquid sulfuric acid (H₂SO₄; 10.94 mmol, 50%;PanReac AppliChem, Darmstadt, Germany; catalog #A2102,2500) and 18 g ofsolid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 11.8 mol % and a 2-APA conversion of ≥97 mol %.

Example 24—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and HBrMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to HBr Equal to 51.4:20:1, Temperature 220° C., and No StripGas

The molten salt catalyst with a molar ratio of 20 was prepared by firstmixing 0.45 g of liquid hydrobromic acid (HBr; 2.61 mmol, 47%; MerckKGaA, Darmstadt, Germany; catalog #1.00304.0500) and 18.01 g of solidtetrabutylphosphonium bromide ([PBu₄]Br; 52.01 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #189138) at room temperatureand atmospheric conditions in a 100 mL three-necked glass reactor, andthen heating the catalyst at a temperature of 220° C. under continuousstirring with an overhead stirrer at a speed of 300 rpm. After themolten salt catalyst reached a constant temperature of 220° C., 17.72 g(134.1 mmol) of synthesized pure 2-APA were fed into the glass reactorat a constant feeding rate of 0.5 mL/min by means of a funnel. The 2-APAwas slowly dropped into the glass reactor and the reaction products weresemi-batchwise removed. The liquid products were condensed and collectedin an ice-cooled flask, and the gaseous by-products were routed to theoff-gas. After an overall process time of 150 min, 1 g of mesitylene(C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #M7200) was added to the distillation flask as internalstandard and the collected distillate, as well as the molten saltcatalyst, were both analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹HqNMR analysis of the distillate gave an acrylic acid yield of about 7.3mol % and a 2-APA conversion of ≥97 mol %.

Example 25—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and HBrMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to HBr Equal to 25.7:10:1, Temperature 220° C., and No StripGas

The molten salt catalyst with a molar ratio of 10 was prepared by firstmixing 0.90 g of liquid hydrobromic acid (HBr; 5.23 mmol, 47%; MerckKGaA, Darmstadt, Germany; catalog #1.00304.0500) and 18.02 g of solidtetrabutylphosphonium bromide ([PBu₄]Br; 52.04 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #189138) at room temperatureand atmospheric conditions in a 100 mL three-necked glass reactor, andthen heating the catalyst at a temperature of 220° C. under continuousstirring with an overhead stirrer at a speed of 300 rpm. After themolten salt catalyst reached a constant temperature of 220° C., 17.78 g(134.6 mmol) of synthesized pure 2-APA were fed into the glass reactorat a constant feeding rate of 0.5 mL/min by means of a funnel. The 2-APAwas slowly dropped into the glass reactor and the reaction products weresemi-batchwise removed. The liquid products were condensed and collectedin an ice-cooled flask, and the gaseous by-products were routed to theoff-gas. After an overall process time of 150 min, 1 g of mesitylene(C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #M7200) was added to the distillation flask as internalstandard and the collected distillate, as well as the molten saltcatalyst, were both analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹HqNMR analysis of the distillate gave an acrylic acid yield of about 13mol % and a 2-APA conversion of ≥97 mol %.

Example 26—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and HBrMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to HBr Equal to 15.7:6:1, Temperature 220° C., and No Strip Gas

The molten salt catalyst with a molar ratio of 6 was prepared by firstmixing 1.47 g of liquid hydrobromic acid (HBr; 8.54 mmol, 47%; MerckKGaA, Darmstadt, Germany; catalog #1.00304.0500) and 18 g of solidtetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #189138) at room temperatureand atmospheric conditions in a 100 mL three-necked glass reactor, andthen heating the catalyst at a temperature of 220° C. under continuousstirring with an overhead stirrer at a speed of 300 rpm. After themolten salt catalyst reached a constant temperature of 220° C., 17.66 g(133.7 mmol) of synthesized pure 2-APA were fed into the glass reactorat a constant feeding rate of 0.5 mL/min by means of a funnel. The 2-APAwas slowly dropped into the glass reactor and the reaction products weresemi-batchwise removed. The liquid products were condensed and collectedin an ice-cooled flask, and the gaseous by-products were routed to theoff-gas. After an overall process time of 150 min, 1 g of mesitylene(C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #M7200) was added to the distillation flask as internalstandard and the collected distillate, as well as the molten saltcatalyst, were both analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹HqNMR analysis of the distillate gave an acrylic acid yield of about 14.3mol % and a 2-APA conversion of ≥97 mol %.

Example 27a—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and HBrMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to HBr Equal to 12.2:4.75:1, Temperature 220° C., and No StripGas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 1.88 g of liquid hydrobromic acid (HBr; 10.94 mmol, 47%;Merck KGaA, Darmstadt, Germany; catalog #1.00304.0500) and 18 g of solidtetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #189138) at room temperatureand atmospheric conditions in a 100 mL three-necked glass reactor, andthen heating the catalyst at a temperature of 220° C. under continuousstirring with an overhead stirrer at a speed of 300 rpm. After themolten salt catalyst reached a constant temperature of 220° C., 17.64 g(133.5 mmol) of synthesized pure 2-APA were fed into the glass reactorat a constant feeding rate of 0.5 mL/min by means of a funnel. The 2-APAwas slowly dropped into the glass reactor and the reaction products weresemi-batchwise removed. The liquid products were condensed and collectedin an ice-cooled flask, and the gaseous by-products were routed to theoff-gas. After an overall process time of 150 min, 1 g of mesitylene(C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #M7200) was added to the distillation flask as internalstandard and the collected distillate, as well as the molten saltcatalyst, were both analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹HqNMR analysis of the distillate gave an acrylic acid yield of about 18.4mol % and a 2-APA conversion of ≥97 mol %.

Example 27b—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and HBrMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to HBr Equal to 12.2:4.75:1, Temperature 160° C., and No StripGas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 1.88 g of liquid hydrobromic acid (HBr; 10.94 mmol, 47%;Merck KGaA, Darmstadt, Germany; catalog #1.00304.0500) and 18 g of solidtetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 99%; Alfa Aesar,Karlsruhe, Germany; catalog #A10868) at room temperature and atmosphericconditions in a 100 mL three-necked glass reactor, and then heating thecatalyst at a temperature of 160° C. under continuous stirring with anoverhead stirrer at a speed of 300 rpm. After the molten salt catalystreached a constant temperature of 160° C., 17.64 g (133.5 mmol) ofsynthesized pure 2-APA were fed into the glass reactor at a constantfeeding rate of 0.2 mL/min by means of a hose pump. The 2-APA was slowlydropped into the glass reactor. No reaction products were semi-batchwiseremoved due to the low reaction temperature of 160° C. The gaseousby-products were routed to the off-gas. After an overall process time of150 min the reaction flask was analyzed via off-line ¹H NMR (JEOL ECX400 MHz). ¹H qNMR analysis of the reaction mixture gave an acrylic acidyield of about 1 mol % and a 2-APA conversion of 66.8 mol %.

Example 27c—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and HBrMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to HBr Equal to 12.2:4.75:1, Temperature 180° C., and No StripGas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 1.88 g of liquid hydrobromic acid (HBr; 10.94 mmol, 47%;Merck KGaA, Darmstadt, Germany; catalog #1.00304.0500) and 18 g of solidtetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 99%; Alfa Aesar,Karlsruhe, Germany; catalog #A10868) at room temperature and atmosphericconditions in a 100 mL three-necked glass reactor, and then heating thecatalyst at a temperature of 180° C. under continuous stirring with anoverhead stirrer at a speed of 300 rpm. After the molten salt catalystreached a constant temperature of 180° C., 17.64 g (133.5 mmol) ofsynthesized pure 2-APA were fed into the glass reactor at a constantfeeding rate of 0.2 mL/min by means of a hose pump. The 2-APA was slowlydropped into the glass reactor. No reaction products were semi-batchwiseremoved due to the low reaction temperature of 180° C. The gaseousby-products were routed to the off-gas. After an overall process time of150 min the reaction flask was analyzed via off-line ¹H NMR (JEOL ECX400 MHz). ¹H qNMR analysis of the reaction mixture gave an acrylic acidyield of about 1 mol % and a 2-APA conversion of 67.0 mol %.

Example 28—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and HBrMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to HBr Equal to 10.3:4:1, Temperature 220° C., and No Strip Gas

The molten salt catalyst with a molar ratio of 4 was prepared by firstmixing 2.23 g of liquid hydrobromic acid (HBr; 12.95 mmol, 47%; MerckKGaA, Darmstadt, Germany; catalog #1.00304.0500) and 18 g of solidtetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #189138) at room temperatureand atmospheric conditions in a 100 mL three-necked glass reactor, andthen heating the catalyst at a temperature of 220° C. under continuousstirring with an overhead stirrer at a speed of 300 rpm. After themolten salt catalyst reached a constant temperature of 220° C., 17.68 g(133.8 mmol) of synthesized pure 2-APA were fed into the glass reactorat a constant feeding rate of 0.5 mL/min by means of a funnel. The 2-APAwas slowly dropped into the glass reactor and the reaction products weresemi-batchwise removed. The liquid products were condensed and collectedin an ice-cooled flask, and the gaseous by-products were routed to theoff-gas. After an overall process time of 150 min, 1 g of mesitylene(C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #M7200) was added to the distillation flask as internalstandard and the collected distillate, as well as the molten saltcatalyst, were both analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹HqNMR analysis of the distillate gave an acrylic acid yield of about 18.5mol % and a 2-APA conversion of ≥97 mol %.

Example 29—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and HBrMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to HBr Equal to 5.1:2:1, Temperature 220° C., and No Strip Gas

The molten salt catalyst with a molar ratio of 2 was prepared by firstmixing 4.47 g of liquid hydrobromic acid (HBr; 25.97 mmol, 47%; MerckKGaA, Darmstadt, Germany; catalog #1.00304.0500) and 18.02 g of solidtetrabutylphosphonium bromide ([PBu₄]Br; 52.04 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #189138) at room temperatureand atmospheric conditions in a 100 mL three-necked glass reactor, andthen heating the catalyst at a temperature of 220° C. under continuousstirring with an overhead stirrer at a speed of 300 rpm. After themolten salt catalyst reached a constant temperature of 220° C., 17.64 g(133.5 mmol) of synthesized pure 2-APA were fed into the glass reactorat a constant feeding rate of 0.5 mL/min by means of a funnel. The 2-APAwas slowly dropped into the glass reactor and the reaction products weresemi-batchwise removed. The liquid products were condensed and collectedin an ice-cooled flask, and the gaseous by-products were routed to theoff-gas. After an overall process time of 150 min, 1 g of mesitylene(C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #M7200) was added to the distillation flask as internalstandard and the collected distillate, as well as the molten saltcatalyst, were both analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹HqNMR analysis of the distillate gave an acrylic acid yield of about 18.7mol % and a 2-APA conversion of ≥97 mol %.

Example 30—Acrylic Acid Synthesis from 2-APA with HBr Acid, Molar Ratioof Lactic Acid Equivalent (LAe) to HBr Equal to 10.3:1, and No Strip Gas

2.46 g of liquid hydrobromic acid (HBr; 14.29 mmol, 47%; Merck KGaA,Darmstadt, Germany; catalog #1.00304.0500) were mixed with 19.41 g(146.9 mmol) of synthesized pure 2-APA, placed in a 100 mL three-neckedglass reactor at room temperature and atmospheric conditions, and thenheated to 220° C. under continuous stirring with an overhead stirrer ata speed of 300 rpm. The liquid products were condensed and collected inan ice-cooled flask, and the gaseous by-products were routed to theoff-gas. After an overall process time of 150 min, 1 g of mesitylene(C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #M7200) was added to the distillation flask as internalstandard and the collected distillate, as well as the residue in thethree-necked glass reactor, were both analyzed via off-line ¹H NMR (JEOLECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylic acidyield of about 0 mol %.

Example 31—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and H₄P₂O₇Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to H₄P₂O₇ Equal to 24.2:4.75:1 Temperature 220° C., and ArgonStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 4.3 g of solid pyrophosphoric acid (H₄P₂O₇; 21.9 mmol,≥90%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #83210)and 36 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 104 mmol,98%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138)at room temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 70 g (530 mmol) of synthesized pure 2-APA were fed into theglass reactor at a constant feeding rate of 0.25 mL/min by means of ahose pump. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed using a water-cooledcondenser and Ar strip gas at 200 mLn/min. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of5 h, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-Aldrich ChemieGmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 32 mol % and a 2-APA conversion of ≥97 mol %.

Example 32—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and H₄P₂O₇Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to H₄P₂O₇ Equal to 17.7:3.5:1, Temperature 220° C., and ArgonStrip Gas

The molten salt catalyst with a molar ratio of 3.5 was prepared by firstmixing 5.9 g of solid pyrophosphoric acid (H₄P₂O₇; 30 mmol, ≥90%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #83210) and 36g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 104 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 70 g (530 mmol) of synthesized pure 2-APA were fed into theglass reactor at a constant feeding rate of 0.25 mL/min by means of ahose pump. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed using a water-cooledcondenser and Ar strip gas at 200 mLn/min. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of5 h, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-Aldrich ChemieGmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 23 mol % and a 2-APA conversion of about ≥97 mol %.

Example 33—Acrylic Acid Synthesis from 2-APA with [PBu₄]Cl and H₄P₂O₇Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Cl to H₄P₂O₇ Equal to 10.8:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 2.44 g of solid pyrophosphoric acid (H₄P₂O₇; 12.34 mmol,≥90%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #83210)and 18 g of solid tetrabutylphosphonium chloride ([PBu₄]Cl; 8.6 mmol,96%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #144800)at room temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of <1 mol %.

Example 34—Acrylic Acid Synthesis from 2-APA with [PBu₄]I and H₄P₂O₇Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]I to H₄P₂O₇ Equal to 13.9:4.75:1, Temperature 220° C., and NoStrip Gas

The molten salt catalyst with a molar ratio of 4.75 was prepared byfirst mixing 1.9 g of solid pyrophosphoric acid (H₄P₂O₇; 9.61 mmol,≥90%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #83210)and 18 g of solid tetrabutylphosphonium iodide ([PBu₄]I; 45.66 mmol,98%; Alfa Aesar GmbH & Co KG, Karlsruhe, Germany; catalog #A16792) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of afunnel. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 1 g of mesitylene (C₆H₃(CH₃)₃; 8.15 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) was added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of <1 mol %.

Example 35—Acrylic Acid Synthesis from 88 wt % Lactic Acid AqueousSolution with [PBu₄]Br and H₄P₂O₇ Molten Salt Catalyst, Molar Ratio ofLactic Acid Equivalent (LAe) to [PBu₄]Br to H₄P₂O₇ Equal to 6.6:3.5:1,Temperature 220° C., and No Strip Gas

The molten salt catalyst with a molar ratio of 3.5 was prepared by firstmixing 2.90 g of solid pyrophosphoric acid (H₄P₂O₇; 14.85 mmol, ≥90%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #83210) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 10 g of an 88 wt % L-lactic acid solution (Corbion Purac Co.,Lenexa, Kans.; 97.8 mmol LAe) were fed into the glass reactor at aconstant feeding rate of 0.33 mL/min by means of a funnel. The LAsolution was slowly dropped into the glass reactor and the reactionproducts were semi-batchwise removed. The liquid products were condensedand collected in an ice-cooled flask, and the gaseous by-products wererouted to the off-gas. After an overall process time of 150 min, 0.5 gof hydroquinone (C₆H₄-1,4-(OH)₂; 4.52 mmol, 99.5%; Sigma-Aldrich ChemieGmbH, Taufkirchen, Germany; catalog #H17902) were added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 4 mol %.

Example 36—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and H₄P₂O₇Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to H₄P₂O₇ Equal to 9:3.5:1, Temperature 220° C., and No StripGas

10 g of solid lactide (C₆H₈O₄; 66.61 mmol, 133.22 mmol LAe, >96%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #303143) wereplaced in a 100 mL three-necked glass reactor. The molten salt catalystwith a molar ratio of 3.5 was prepared by mixing 2.90 g of solidpyrophosphoric acid (H₄P₂O₇; 14.85 mmol, ≥90%; Sigma-Aldrich ChemieGmbH, Taufkirchen, Germany; catalog #83210) and 18 g of solidtetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #189138) at room temperatureand atmospheric conditions in the 100 mL three-necked glass reactor, andthen heating the catalyst and the reactant at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. While the molten salt catalyst and the reactant were kept at aconstant temperature of 220° C. the reaction products weresemi-batchwise removed. The liquid products were condensed and collectedin an ice-cooled flask, and the gaseous by-products were routed to theoff-gas. After an overall process time of 150 min, 0.5 g of hydroquinone(C₆H₄-1,4-(OH)₂; 4.52 mmol, 99.5%; Sigma-Aldrich Chemie GmbH,Taufkirchen, Germany; catalog #H17902) were added to the distillationflask as internal standard and the collected distillate, as well as themolten salt catalyst, were both analyzed via off-line ¹H NMR (JEOL ECX400 MHz). ¹H qNMR analysis of the distillate gave an acrylic acid yieldof about 8.8 mol %.

Example 37—Acrylic Acid Synthesis from ETFP with [PBu₄]Br and H₄P₂O₇Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to H₄P₂O₇ Equal to 3.1:3.5:1, Temperature 220° C., and No StripGas

The molten salt catalyst with a molar ratio of 3.5 was prepared by firstmixing 2.90 g of solid pyrophosphoric acid (H₄P₂O₇; 14.85 mmol, ≥90%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #83210) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 10 g (46.7 mmol) of synthesized pure ETFP were fed into theglass reactor at a constant feeding rate of 0.33 mL/min by means of afunnel. The ETFP was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 0.5 g of mesitylene (C₆H₃(CH₃)₃; 4.08 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) were added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 15.6 mol %.

Example 38—Acrylic Acid Synthesis from EAPA with [PBu₄]Br and H₄P₂O₇Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to H₄P₂O₇ Equal to 4.2:3.5:1, Temperature 220° C., and No StripGas

The molten salt catalyst with a molar ratio of 3.5 was prepared by firstmixing 2.90 g of solid pyrophosphoric acid (H₄P₂O₇; 14.85 mmol, ≥90%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #83210) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 10 g (62.4 mmol) of synthesized pure EAPA were fed into theglass reactor at a constant feeding rate of 0.33 mL/min by means of afunnel. The EAPA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 0.5 g of mesitylene (C₆H₃(CH₃)₃; 4.08 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) were added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 2.8 mol %.

Example 39—Acrylic Acid Synthesis from 2-TFPA with [PBu₄]Br and H₄P₂O₇Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to H₄P₂O₇ Equal to 3.6:3.5:1, Temperature 220° C., and No StripGas

The molten salt catalyst with a molar ratio of 3.5 was prepared by firstmixing 2.90 g of solid pyrophosphoric acid (H₄P₂O₇; 14.85 mmol, ≥90%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #83210) and 18g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 51.99 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) atroom temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 10 g (53.8 mmol) of synthesized pure 2-TFPA were fed into theglass reactor at a constant feeding rate of 0.33 mL/min by means of afunnel. The 2-TFPA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 0.5 g of mesitylene (C₆H₃(CH₃)₃; 4.08 mmol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #M7200) were added to thedistillation flask as internal standard and the collected distillate, aswell as the molten salt catalyst, were both analyzed via off-line ¹H NMR(JEOL ECX 400 MHz). ¹H qNMR analysis of the distillate gave an acrylicacid yield of about 5 mol %.

Example 40—Acrylic Acid Synthesis from 2-APA with [pTolPPh₃]Br and HBrMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[pTolPPh₃]Br to HBr Equal to 9.3:4:1, Temperature 220° C., and No StripGas

The molten salt catalyst with a molar ratio of 4 was prepared by firstmixing 2.43 g of liquid hydrobromic acid (HBr; 14.42 mmol, 48%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #244260) and 25g of solid (p-tolyl)triphenylphosphonium bromide ([pTolPPh₃]Br; 57.69mmol, 100%) at room temperature and atmospheric conditions in a 100 mLthree-necked glass reactor, and then heating the catalyst at atemperature of 220° C. under continuous stirring with an overheadstirrer at a speed of 300 rpm. After the molten salt catalyst reached aconstant temperature of 220° C., 17.64 g (133.5 mmol) of synthesizedpure 2-APA were fed into the glass reactor at a constant feeding rate of0.5 mL/min by means of a hose pump. The 2-APA was slowly dropped intothe glass reactor and the reaction products were semi-batchwise removed.The liquid products were condensed and collected in an ice-cooled flask,and the gaseous by-products were routed to the off-gas. After an overallprocess time of 150 min, 0.1 g of 3-(Trimethylsilyl)-1-propanesulfonicacid sodium salt (0.44 mmol, 97%; Sigma-Aldrich Chemie GmbH,Taufkirchen, Germany; catalog #178837) was added to the distillationflask as internal standard and the collected distillate, as well as themolten salt catalyst, were both analyzed via off-line ¹H NMR (JEOL ECX400 MHz). ¹H qNMR analysis of the distillate gave an acrylic acid yieldof about 7.8 mol % and a 2-APA conversion of ≥97 mol %.

Example 41—Acrylic Acid Synthesis from 2-APA with [EtPPh₃]Br and HBrMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[EtPPh₃]Br to HBr Equal to 10:4:1, Temperature 220° C., and No Strip Gas

The molten salt catalyst with a molar ratio of 4 was prepared by firstmixing 2.25 g of liquid hydrobromic acid (HBr; 13.35 mmol, 48%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #244260) and 20g of solid ethyltriphenylphosphonium bromide ([EtPPh₃]Br; 53.33 mmol,99%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #E50604)at room temperature and atmospheric conditions in a 100 mL three-neckedglass reactor, and then heating the catalyst at a temperature of 220° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the molten salt catalyst reached a constant temperature of220° C., 17.64 g (133.5 mmol) of synthesized pure 2-APA were fed intothe glass reactor at a constant feeding rate of 0.5 mL/min by means of ahose pump. The 2-APA was slowly dropped into the glass reactor and thereaction products were semi-batchwise removed. The liquid products werecondensed and collected in an ice-cooled flask, and the gaseousby-products were routed to the off-gas. After an overall process time of150 min, 0.1 g of 3-(Trimethylsilyl)-1-propanesulfonic acid sodium salt(0.44 mmol, 97%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany;catalog #178837) was added to the distillation flask as internalstandard and the collected distillate, as well as the molten saltcatalyst, were both analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹HqNMR analysis of the distillate gave an acrylic acid yield of about 25mol % and a 2-APA conversion of ≥97 mol %.

Tabulated results from Examples 1 to 41 can be seen in Table 1 below.All reactions were conducted at a constant temperature of the moltensalt catalyst of 220° C., except where noted, and with no strip gas,except where noted.

TABLE 1 Molar Ratio of Feed (LAe) to Acrylic Acid Example FeedCatalyst - Catalyst - IL to Acid, Yield, # Material IL Acid [—] [mol %] 1 2-APA [PBu₄]Br — 2.57:1:— 1.3  2 2-APA [PBu₄]Br H₄P₂O₇ 71.8:28:1 5.5 3 2-APA [PBu₄]Br H₄P₂O₇ 36:14:1 7.0  4 2-APA [PBu₄]Br H₄P₂O₇ 18:7:1 9.6 5 2-APA [PBu₄]Br H₄P₂O₇ 12.2:4.75:1 11.1  6 2-APA [PBu₄]Br H₄P₂O₇9:3.5:1 8.8  7 2-APA [PBu₄]Br H₄P₂O₇ 2.57:1:1 1.4  8 2-APA — H₄P₂O₇1.47:0:1 0  9 2-APA [PBu₄]Br KBr 12.2:4.75:1 0.7 10 2-APA [PBu₄]Br CaBr₂12.2:4.75:1 11.8 11 2-APA [PBu₄]Br MgBr₂ 12.2:4.75:1 12.9 12 2-APA[PBu₄]Br AlBr₃ 12.2:4.75:1 14.3 13 2-APA [PBu₄]Br InBr₃ 12.2:4.75:1 0.814 2-APA [PBu₄]Br NiBr₂ 12.2:4.75:1 0.5 15 2-APA [PBu₄]Br CoBr₂12.2:4.75:1 0.6 16 2-APA [PBu₄]Br ZnBr₂ 12.2:4.75:1 0.7 17 2-APA[PBu₄]Br FeBr₃ 12.2:4.75:1 1.0 18 2-APA [PBu₄]Br GaBr₃ 14.95:4.75:1 1.219 2-APA [PBu₄]Br CuBr₂ 12.2:4.75:1 8.2 20 2-APA [PBu₄]Br HBr/AlBr₃12.2:4.75:1 9.9 21 2-APA [PBu₄]Br CH₃CO₂H 12.2:4.75:1 3.4 22 2-APA[PBu₄]Br H₃PO₄ 12.2:4.75:1 6.2 23 2-APA [PBu₄]Br H₂SO₄ 12.2:4.75:1 11.824 2-APA [PBu₄]Br HBr 51.4:20:1 7.3 25 2-APA [PBu₄]Br HBr 25.7:10:1 1326 2-APA [PBu₄]Br HBr 15.7:6:1 14.3  27a 2-APA [PBu₄]Br HBr 12.2:4.75:118.4  27b* 2-APA [PBu₄]Br HBr 12.2:4.75:1 1   27c** 2-APA [PBu₄]Br HBr12.2:4.75:1 1 28 2-APA [PBu₄]Br HBr 10.3:4:1 18.5 29 2-APA [PBu₄]Br HBr5.1:2:1 18.7 30 2-APA — HBr 10.3:0:1 0  31{circumflex over ( )} 2-APA[PBu₄]Br H₄P₂O₇ 24.2:4.75:1 32  32{circumflex over ( )} 2-APA [PBu₄]BrH₄P₂O₇ 17.7:3.5:1 23 33 2-APA [PBu₄]Cl H₄P₂O₇ 10.8:4.75:1 <1 34 2-APA[PBu₄]I H₄P₂O₇ 13.9:4.75:1 <1 35 88 wt % LA [PBu₄]Br H₄P₂O₇ 6.6:3.5:1 436 Lactide [PBu₄]Br H₄P₂O₇ 9:3.5:1 8.8 37 ETFP [PBu₄]Br H₄P₂O₇ 3.1:3.5:115.6 38 EAPA [PBu₄]Br H₄P₂O₇ 4.2:3.5:1 2.8 39 2-TFPA [PBu₄]Br H₄P₂O₇3.6:3.5:1 5 40 2-APA [pTolPPh₃]Br HBr 9.3:4:1 7.8 41 2-APA [EtPPh₃]BrHBr 10:4:1 25 *Conducted at a constant temperature of the molten saltcatalyst of 160° C. **Conducted at a constant temperature of the moltensalt catalyst of 180° C. {circumflex over ( )}Ar strip gasExample 42—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:1:0.1, Temperature 150° C., and ReactionTime 48 h

17.31 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 50 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.60 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were mixed at room temperature and atmosphericconditions in a 100 mL three-necked glass reactor. 0.77 g of liquid2-bromopropionic acid (2-BrPA; 5 mmol, 99%; Sigma-Aldrich Chemie GmbH,Taufkirchen, Germany; catalog #B78300) was added to the reactionmixture, thus generating a molar ratio of [PBu₄]Br and 2-BrPA of 10.Then, the reaction mixture was heated to a reaction temperature of 150°C. under continuous stirring with an overhead stirrer at a speed of 300rpm. After the reaction mixture reached a constant temperature of 150°C., the system was batchwise refluxed and gaseous by-products wererouted to the off-gas or collected in a hydrostatic column. After anoverall process time of 48 h, the hot molten salt is allowed to cooldown to room temperature and analyzed via off-line ¹H NMR (JEOL ECX 400MHz). ¹H qNMR analysis of the reaction mixture gave an acrylic acidyield of about 47 mol %.

Example 43—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Temperature 110° C., and ReactionTime 168 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.77 g ofliquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #B78300) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to2-BrPA equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 110° C. under continuous stirring with anoverhead stirrer at a speed of 300 rpm. After the reaction mixturereached a constant temperature of 110° C., the system was batchwiserefluxed and gaseous by-products were routed to the off-gas or collectedin a hydrostatic column. After a reaction time of 168 h, the hot moltensalt was allowed to cool down to room temperature and was analyzed viaoff-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of the reactionmixture gave an acrylic acid yield (AAY) of about 24 mol %.

Example 44—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Temperature 130° C., and ReactionTime 168 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.77 g ofliquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #B78300) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to2-BrPA equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 130° C. under continuous stirring with anoverhead stirrer at a speed of 300 rpm. After the reaction mixturereached a constant temperature of 130° C., the system was batchwiserefluxed and gaseous by-products were routed to the off-gas or collectedin a hydrostatic column. After a reaction time of 168 h, the hot moltensalt was allowed to cool down to room temperature and was analyzed viaoff-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of the reactionmixture gave an acrylic acid yield (AAY) of about 44 mol %.

Example 45—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Temperature 150° C., and ReactionTime 48 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.60 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were mixed at room temperature and atmosphericconditions in a 100 mL three-necked glass reactor. 0.77 g of liquid2-bromopropionic acid (2-BrPA; 5 mmol, 99%; Sigma-Aldrich Chemie GmbH,Taufkirchen, Germany; catalog #B78300) was added to the reactionmixture, thus generating a molar ratio of [PBu₄]Br and 2-BrPA of 20.Then, the reaction mixture was heated to a reaction temperature of 150°C. under continuous stirring with an overhead stirrer at a speed of 300rpm. After the reaction mixture reached a constant temperature of 150°C., the system was batchwise refluxed and gaseous by-products wererouted to the off-gas or collected in a hydrostatic column. After anoverall process time of 48 h, the hot molten salt is allowed to cooldown to room temperature and analyzed via off-line ¹H NMR (JEOL ECX 400MHz). ¹H qNMR analysis of the reaction mixture gave an acrylic acidyield of about 52 mol %.

Example 46—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Temperature 150° C., and ReactionTime 96 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and5.12 g of liquid lactic acid (50 mmol, 88%; Corbion Purac Co., Lenexa,Kans.) were first mixed at room temperature and atmospheric conditionsin a 100 mL three-necked glass reactor. 0.77 g of liquid 2-BrPA (5 mmol,99%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #B78300)was then added to the reaction mixture, thus generating a molar ratio oflactic acid equivalent (LAe) to [PBu₄]Br to 2-BrPA equal to 1:2:0.1. Thereaction mixture was then heated to a reaction temperature of 150° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the reaction mixture reached a constant temperature of 150°C., the system was batchwise refluxed and gaseous by-products wererouted to the off-gas or collected in a hydrostatic column. After areaction time of 96 h, the hot molten salt was allowed to cool down toroom temperature and was analyzed via off-line ¹H NMR (JEOL ECX 400MHz). ¹H qNMR analysis of the reaction mixture gave an acrylic acidyield (AAY) of about 31 mol %.

Example 47—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Temperature 150° C., and ReactionTime 168 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and6.03 g of liquid ethyl lactate (50 mmol, 99%; Sigma-Aldrich Chemie GmbH,Taufkirchen, Germany; catalog #W244007) were first mixed at roomtemperature and atmospheric conditions in a 100 mL three-necked glassreactor. 0.77 g of liquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich ChemieGmbH, Taufkirchen, Germany; catalog #B78300) was then added to thereaction mixture, thus generating a molar ratio of lactic acidequivalent (LAe) to [PBu₄]Br to 2-BrPA equal to 1:2:0.1. The reactionmixture was then heated to a reaction temperature of 150° C. undercontinuous stirring with an overhead stirrer at a speed of 300 rpm.After the reaction mixture reached a constant temperature of 150° C.,the system was batchwise refluxed and gaseous by-products were routed tothe off-gas or collected in a hydrostatic column. After a reaction timeof 168 h, the hot molten salt was allowed to cool down to roomtemperature and was analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹HqNMR analysis of the reaction mixture gave an acrylic acid yield (AAY)of about 7 mol %.

Example 48—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Temperature 160° C., and ReactionTime 24 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.77 g ofliquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #B78300) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to2-BrPA equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 160° C. under continuous stirring with anoverhead stirrer at a speed of 300 rpm. After the reaction mixturereached a constant temperature of 160° C., the system was batchwiserefluxed and gaseous by-products were routed to the off-gas or collectedin a hydrostatic column. After a reaction time of 24 h, the hot moltensalt was allowed to cool down to room temperature and was analyzed viaoff-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of the reactionmixture gave an acrylic acid yield (AAY) of about 58 mol %.

Example 49—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Temperature 170° C., and ReactionTime 7 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.77 g ofliquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #B78300) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to2-BrPA equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 170° C. under continuous stirring with anoverhead stirrer at a speed of 300 rpm. After the reaction mixturereached a constant temperature of 170° C., the system was batchwiserefluxed and gaseous by-products were routed to the off-gas or collectedin a hydrostatic column. After a reaction time of 7 h, the hot moltensalt was allowed to cool down to room temperature and was analyzed viaoff-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of the reactionmixture gave an acrylic acid yield (AAY) of about 56 mol %.

Example 50—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Temperature 190° C., and ReactionTime 2 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.77 g ofliquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #B78300) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to2-BrPA equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 190° C. under continuous stirring with anoverhead stirrer at a speed of 300 rpm. After the reaction mixturereached a constant temperature of 190° C., the system was batchwiserefluxed and gaseous by-products were routed to the off-gas or collectedin a hydrostatic column. After a reaction time of 2 h, the hot moltensalt was allowed to cool down to room temperature and was analyzed viaoff-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of the reactionmixture gave an acrylic acid yield (AAY) of about 54 mol %.

Example 51—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Temperature 220° C., and ReactionTime 0.33 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.77 g ofliquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #B78300) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to2-BrPA equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 220° C. under continuous stirring with anoverhead stirrer at a speed of 300 rpm. After the reaction mixturereached a constant temperature of 220° C., the system was batchwiserefluxed and gaseous by-products were routed to the off-gas or collectedin a hydrostatic column. After a reaction time of 0.33 h, the hot moltensalt was allowed to cool down to room temperature and was analyzed viaoff-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of the reactionmixture gave an acrylic acid yield (AAY) of about 50 mol %.

Tabulated results from Examples 42 to 51 can be seen in Table 2 below.In all Examples, the molten salt catalyst included [PBu₄]Br and 2-BrPA,and lactide was the lactic acid derivative included in the feed stream.

TABLE 2 Molar Ratio of LAe to [PBu₄]Br Reaction Reaction Acrylic Acid to2-BrPA, Temperature, Time, Yield, Example # [—] [° C.] [h] [mol %] 421:1:0.1 150 48 47 43 1:2:0.1 110 168 24 44 1:2:0.1 130 168 44 45 1:2:0.1150 48 52 46 1:2:0.1 150 96 31 47 1:2:0.1 150 168 7 48 1:2:0.1 160 24 5849 1:2:0.1 170 7 56 50 1:2:0.1 190 2 54 51 1:2:0.1 220 0.33 50Example 52—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and MgBr₂Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to MgBr₂ Equal to 1:2:0.1, Temperature 150° C., and ReactionTime 48 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.94 g ofsolid MgBr₂ (5 mmol, 98%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #360074) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br toMgBr₂ equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 150° C. under continuous stirring with anoverhead stirrer at a speed of 300 rpm. After the reaction mixturereached a constant temperature of 150° C., the system was batchwiserefluxed and gaseous by-products were routed to the off-gas or collectedin a hydrostatic column. After a reaction time of 48 h, the hot moltensalt was allowed to cool down to room temperature and was analyzed viaoff-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of the reactionmixture gave an acrylic acid yield (AAY) of about 56 mol %.

Example 53—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and H₄P₂O₇Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to H₄P₂O₇ Equal to 1:2:0.1, Temperature 150° C., and ReactionTime 96.5 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.99 g ofsolid H₄P₂O₇ (5 mmol, 90%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #83210) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br toH₄P₂O₇ equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 150° C. under continuous stirring with anoverhead stirrer at a speed of 300 rpm. After the reaction mixturereached a constant temperature of 150° C., the system was batchwiserefluxed and gaseous by-products were routed to the off-gas or collectedin a hydrostatic column. After a reaction time of 96.5 h, the hot moltensalt was allowed to cool down to room temperature and was analyzed viaoff-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of the reactionmixture gave an acrylic acid yield (AAY) of about 47 mol %.

Example 54—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and HBrMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to HBr Equal to 1:2:0.1, Temperature 150° C., and Reaction Time71 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.84 g ofliquid HBr (5 mmol, 48%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #244260) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br toHBr equal to 1:2:0.1. The reaction mixture was then heated to a reactiontemperature of 150° C. under continuous stirring with an overheadstirrer at a speed of 300 rpm. After the reaction mixture reached aconstant temperature of 150° C., the system was batchwise refluxed andgaseous by-products were routed to the off-gas or collected in ahydrostatic column. After a reaction time of 71 h, the hot molten saltwas allowed to cool down to room temperature and was analyzed viaoff-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of the reactionmixture gave an acrylic acid yield (AAY) of about 43 mol %.

Example 55—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and AceticAcid Molten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe)to [PBu₄]Br to Acetic Acid Equal to 1:2:0.1, Temperature 150° C., andReaction Time 168 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.3 g ofliquid acetic acid (5 mmol, 100%; VWR International GmbH, Darmstadt,Germany; catalog #20104.334) was then added to the reaction mixture,thus generating a molar ratio of lactic acid equivalent (LAe) to[PBu₄]Br to acetic acid equal to 1:2:0.1. The reaction mixture was thenheated to a reaction temperature of 150° C. under continuous stirringwith an overhead stirrer at a speed of 300 rpm. After the reactionmixture reached a constant temperature of 150° C., the system wasbatchwise refluxed and gaseous by-products were routed to the off-gas orcollected in a hydrostatic column. After a reaction time of 168 h, thehot molten salt was allowed to cool down to room temperature and wasanalyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of thereaction mixture gave an acrylic acid yield (AAY) of about 30 mol %.

Example 56—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and NoFurther Acid, Molar Ratio of Lactic Acid Equivalent (LAe) to [PBu₄]BrEqual to 1:2, Temperature 150° C., and Reaction Time 168 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were mixed at room temperature and atmosphericconditions in a 100 mL three-necked glass reactor, thus generating amolar ratio of lactic acid equivalent (LAe) to [PBu₄]Br equal to 1:2.The reaction mixture was then heated to a reaction temperature of 150°C. under continuous stirring with an overhead stirrer at a speed of 300rpm. After the reaction mixture reached a constant temperature of 150°C., the system was batchwise refluxed and gaseous by-products wererouted to the off-gas or collected in a hydrostatic column. After areaction time of 168 h, the hot molten salt was allowed to cool down toroom temperature and was analyzed via off-line ¹H NMR (JEOL ECX 400MHz). ¹H qNMR analysis of the reaction mixture gave an acrylic acidyield (AAY) of about 32 mol %.

Tabulated results from Examples 52 to 56 can be seen in Table 3 below.In all Examples, lactide was the lactic acid derivative included in thefeed stream, and the molar ratio of lactic acid equivalent (LAe) to[PBu₄]Br to acid was equal to 1:2:0.1.

TABLE 3 Acid in the Reaction Reaction Acrylic Acid Molten SaltTemperature, Time, Yield, Example # Catalyst [° C.] [h] [mol %] 52 MgBr₂150 48 56 53 H₄P₂O₇ 150 96.5 47 54 HBr 150 71 43 55 Acedtic Acid 150 16830 56 None 150 168 32Example 57—Acrylic Acid Synthesis from 2-APA with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Temperature 150° C., and ReactionTime 168 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and6.88 g of synthesized pure 2-APA (50 mmol) were first mixed at roomtemperature and atmospheric conditions in a 100 mL three-necked glassreactor. 0.77 g of liquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich ChemieGmbH, Taufkirchen, Germany; catalog #B78300) was then added to thereaction mixture, thus generating a molar ratio of lactic acidequivalent (LAe) to [PBu₄]Br to 2-BrPA equal to 1:2:0.1. The reactionmixture was then heated to a reaction temperature of 150° C. undercontinuous stirring with an overhead stirrer at a speed of 300 rpm.After the reaction mixture reached a constant temperature of 150° C.,the system was batchwise refluxed and gaseous by-products were routed tothe off-gas or collected in a hydrostatic column. After a reaction timeof 168 h, the hot molten salt was allowed to cool down to roomtemperature and was analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹HqNMR analysis of the reaction mixture gave an acrylic acid yield (AAY)of about 42 mol %.

Example 58—Acrylic Acid Synthesis from 2-Formyloxypropionic Acid (2-FPA)with [PBu₄]Br and 2-BrPA Molten Salt Catalyst, Molar Ratio of LacticAcid Equivalent (LAe) to [PBu₄]Br to 2-BrPA Equal to 1:2.5:0.125,Temperature 150° C., and Reaction Time 72 h

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and4.62 g of synthesized pure 2-FPA (40 mmol) were first mixed at roomtemperature and atmospheric conditions in a 100 mL three-necked glassreactor. 0.77 g of liquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich ChemieGmbH, Taufkirchen, Germany; catalog #B78300) was then added to thereaction mixture, thus generating a molar ratio of lactic acidequivalent (LAe) to [PBu₄]Br to 2-BrPA equal to 1:2.5:0.125. Thereaction mixture was then heated to a reaction temperature of 150° C.under continuous stirring with an overhead stirrer at a speed of 300rpm. After the reaction mixture reached a constant temperature of 150°C., the system was batchwise refluxed and gaseous by-products wererouted to the off-gas or collected in a hydrostatic column. After areaction time of 72 h, the hot molten salt was allowed to cool down toroom temperature and was analyzed via off-line ¹H NMR (JEOL ECX 400MHz). ¹H qNMR analysis of the reaction mixture gave an acrylic acidyield (AAY) of about 35 mol %.

Example 59—2-BrPA Synthesis from Lactide with [MIMBS]Br Molten SaltCatalyst

The molten salt bromination medium was prepared by first mixing 16.370 gof solid MIMBS (75 mmol, J. Mater. Chem., 2001, 11, 1057-1062), 12.642 gof 48 wt % hydrobromic acid (HBr; 75 mmol, 48%; Sigma-Aldrich ChemieGmbH, Taufkirchen, Germany; catalog #244260) and 64 g of cyclohexane(C₆H₁₂, 0.76 mol, >99.5%, Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #33117) at room temperature and atmospheric conditionsin a 100 mL three-necked glass reactor. The biphasic reaction mixturewas heated to a temperature of 69.8° C. under continuous stirring with amagnetic stirring bar at a speed of 600 rpm. The protic and HBr loadedionic liquid [MIMBS]Br was received by removing the water using aDean-Stark-apparatus with external heating to 90° C. and finallydecanting the cyclohexane phase after the glass reactor was cooled downto room temperature. After reaction the desired acid amount (75 mmol)was readjusted by adding 3.4 g of 48 wt % hydrobromic acid (HBr; 20mmol, 48%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog#244260). 1.8 g of solid lactide (12.5 mmol, L,L lactide, polymer grade,Corbion Purac Co., Lenexa, Kans.) were added to the reactor and theactivated reaction mixture was heated to 120° C. under continuousstirring with an overhead stirrer at a speed of 600 rpm. The reactionmixture was batchwise refluxed and gaseous by-products were routed tothe off-gas or collected in a hydrostatic column. After an overallprocess time of 300 min, the reaction mixture was quenched with 7.92 gof methanol (CH₃OH, 0.25 mol, 99.8%, anhydrous, Sigma-Aldrich ChemieGmbH, Taufkirchen, Germany; catalog #322415) and the reaction mixturewas analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis ofthe reaction mixture gave a 2-BrPA yield of about 60 mol % andselectivity of more than about 95 mol %.

Example 60—Acrylic Acid Synthesis from 2-BrPA with [PBu₄]Br Molten SaltCatalyst

46.23 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 133.5 mmol,98%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138)were mixed with 2.29 g of liquid 2-bromopropionic acid (2-BrPA; 14.83mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog#B78300) in a 100 mL three-necked glass reactor in a molar ratio of 9:1at room temperature and atmospheric conditions. The reaction mixture washeated to 160° C. under continuous stirring with a magnetic stirring barat a speed of 450 rpm. The reaction mixture mixture was batchwiserefluxed and gaseous by-products were routed to the off-gas or collectedin a hydrostatic column. After an overall process time of 3 h, the hotreaction mixture was allowed to cool down to room temperature and wasanalyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysis of thereaction mixture gave a acrylic acid (AA) yield of about 47 mol % andselectivity of more than about 81 mol %.

Example 61—3-BrPA Synthesis from 2-BrPA with [PBu₄]Br Molten SaltCatalyst

46.23 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 133.5 mmol,98%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138)were mixed with 20.68 g of liquid 2-bromopropionic acid (2-BrPA; 133.5mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog#B78300) in a 100 mL three-necked glass reactor in a molar ratio of 1:1at room temperature and atmospheric conditions. The isomerizationmixture was heated to 160° C. under continuous stirring with a magneticstirring bar at a speed of 450 rpm. The isomerization mixture wasbatchwise refluxed and gaseous by-products were routed to the off-gas orcollected in a hydrostatic column. After an overall process time of 20h, the hot reaction mixture was allowed to cool down to room temperatureand was analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMRanalysis of the isomerization mixture gave a 3-bromopropionic acid(3-BrPA) yield of about 79 mol % and selectivity of more than about 90mol %.

Example 62—Acrylic Acid Synthesis from 3-BrPA with Trioctylamine (TOA)

285 g of trioctylamine ([CH₃(CH₂)₇]₃N; 0.8 mol, 98%; Sigma-AldrichChemie GmbH, Taufkirchen, Germany; catalog #T81000) were mixed with123.4 g of solid 3-bromopropionic acid (3-BrPA; 0.8 mol, 97%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #101281) in athree-necked glass reactor in a molar ratio of 1:1 at room temperatureand atmospheric conditions. The reaction mixture was heated to 180° C.under continuous stirring with a magnetic stirring bar at a speed of 500rpm. After the reaction mixture reached a constant temperature of 180°C., the reaction products were semi-batchwise removed under reducedpressure (90-100 mbar). The liquid products were condensed and collectedin an ice-cooled flask, and the gaseous by-products were routed to theoff-gas. After an overall process time of 30 min the collecteddistillate was analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMRanalysis of the product mixture gave an acrylic acid yield of about 90mol % and selectivity of more than about 90 mol %.

Example 63—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, and Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Using In-Situ Product Removal ViaReactive Distillation at 100 Mbar for 3 Hours

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.77 g ofliquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #B78300) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to2-BrPA equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 190° C. under continuous stirring with amagnetic stirrer at a speed of 800 to 1200 rpm. After the reactionmixture reached a constant temperature of 190° C., a pressure of 100mbar was applied to start the reactive distillation. The products werecollected in cooling trap(s) at temperatures between 0 to −197° C. After3 hours of reactive distillation the reaction was stopped. Under thechosen reaction conditions polymerization of the highly pure acrylicacid took place in the experimental setup. Therefore no yield wasdetermined.

Example 64—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, and Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Using In-Situ Product Removal ViaReactive Distillation at 50 Mbar for 3 Hours

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.77 g ofliquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #B78300) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to2-BrPA equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 190° C. under continuous stirring with amagnetic stirrer at a speed of 800 to 1200 rpm. After the reactionmixture reached a constant temperature of 190° C., a pressure of 50 mbarwas applied to start the reactive distillation. The products werecollected in cooling trap(s) at temperatures between 0 to −197° C. After3 hours of reactive distillation the reaction was stopped. Under thechosen reaction conditions polymerization of the highly pure acrylicacid took place in the experimental setup. Therefore no yield wasdetermined.

Example 65—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, and Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Using In-Situ Product Removal ViaReactive Distillation at 20 Mbar for 3 Hours

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.77 g ofliquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #B78300) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to2-BrPA equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 190° C. under continuous stirring with amagnetic stirrer at a speed of 800 to 1200 rpm. After the reactionmixture reached a constant temperature of 190° C., a pressure of 20 mbarwas applied to start the reactive distillation. The products werecollected in cooling trap(s) at temperatures between 0 to −197° C.By-products were routed to the off-gas. Under the chosen reactionconditions polymerization of the highly pure acrylic acid took place inthe experimental setup. Therefore no yield was determined.

Example 66—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, and Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Using In-Situ Product Removal ViaReactive Distillation at 10 Mbar for 3 Hours

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.77 g ofliquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #B78300) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to2-BrPA equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 190° C. under continuous stirring with amagnetic stirrer at a speed of 800 to 1200 rpm. After the reactionmixture reached a constant temperature of 190° C., a pressure of 10 mbarwas applied to start the reactive distillation. The products werecollected in cooling trap(s) at temperatures between 0 to −197° C. After3 hours of reactive distillation, the hot molten salt and the distillatewere analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysisof the reaction mixture gave an acrylic acid yield of about 11 mol %, ¹HqNMR analysis of the distillate gave an acrylic acid yield of about 69mol %, giving an overall acrylic acid yield in this reactivedistillation of about 80 mol %.

Example 67—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, and Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Using In-Situ Product Removal ViaReactive Distillation at 5 Mbar for 3 Hours

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.77 g ofliquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #B78300) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to2-BrPA equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 190° C. under continuous stirring with amagnetic stirrer at a speed of 800 to 1200 rpm. After the reactionmixture reached a constant temperature of 190° C., a pressure of 5 mbarwas applied to start the reactive distillation. The products werecollected in cooling trap(s) at temperatures between 0 to −197° C. After3 hours of reactive distillation, the hot molten salt and the distillatewere analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysisof the reaction mixture gave an acrylic acid yield of about 8 mol %, ¹HqNMR analysis of the distillate gave an acrylic acid yield of about 62mol %, giving an overall acrylic acid yield in this reactivedistillation of about 70 mol %.

Example 68—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, and Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Using In-Situ Product Removal ViaReactive Distillation at 10 Mbar for 1 Hour

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.77 g ofliquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #B78300) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to2-BrPA equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 190° C. under continuous stirring with amagnetic stirrer at a speed of 800 to 1200 rpm. After the reactionmixture reached a constant temperature of 190° C., a pressure of 10 mbarwas applied to start the reactive distillation. The products werecollected in cooling trap(s) at temperatures between 0 to −197° C. After1 hour of reactive distillation, the hot molten salt and the distillatewere analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysisof the reaction mixture gave an acrylic acid yield of about 24 mol %, ¹HqNMR analysis of the distillate gave an acrylic acid yield of about 29mol %, giving an overall acrylic acid yield in this reactivedistillation of about 53 mol %.

Example 69—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, and Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Using In-Situ Product Removal ViaReactive Distillation at 10 Mbar for 2 Hours

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.77 g ofliquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #B78300) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to2-BrPA equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 190° C. under continuous stirring with amagnetic stirrer at a speed of 800 to 1200 rpm. After the reactionmixture reached a constant temperature of 190° C., a pressure of 10 mbarwas applied to start the reactive distillation. The products werecollected in cooling trap(s) at temperatures between 0 to −197° C. After2 hours of reactive distillation, the hot molten salt and the distillatewere analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysisof the reaction mixture gave an acrylic acid yield of about 20 mol %, ¹HqNMR analysis of the distillate gave an acrylic acid yield of about 42mol %, giving an overall acrylic acid yield in this reactivedistillation of about 62 mol %.

Example 70—Acrylic Acid Synthesis from Lactide with [PBu₄]Br and 2-BrPAMolten Salt Catalyst, and Molar Ratio of Lactic Acid Equivalent (LAe) to[PBu₄]Br to 2-BrPA Equal to 1:2:0.1, Using In-Situ Product Removal ViaReactive Distillation at 10 Mbar for 4 Hours

34.62 g of solid tetrabutylphosphonium bromide ([PBu₄]Br; 100 mmol, 98%;Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany; catalog #189138) and3.6 g of solid lactide (25 mmol, L,L lactide, polymer grade, CorbionPurac Co., Lenexa, Kans.) were first mixed at room temperature andatmospheric conditions in a 100 mL three-necked glass reactor. 0.77 g ofliquid 2-BrPA (5 mmol, 99%; Sigma-Aldrich Chemie GmbH, Taufkirchen,Germany; catalog #B78300) was then added to the reaction mixture, thusgenerating a molar ratio of lactic acid equivalent (LAe) to [PBu₄]Br to2-BrPA equal to 1:2:0.1. The reaction mixture was then heated to areaction temperature of 190° C. under continuous stirring with amagnetic stirrer at a speed of 800 to 1200 rpm. After the reactionmixture reached a constant temperature of 190° C., a pressure of 10 mbarwas applied to start the reactive distillation. The products werecollected in cooling trap(s) at temperatures between 0 to −197° C. After4 hours of reactive distillation, the hot molten salt and the distillatewere analyzed via off-line ¹H NMR (JEOL ECX 400 MHz). ¹H qNMR analysisof the reaction mixture gave an acrylic acid yield of about 3 mol %, ¹HqNMR analysis of the distillate gave an acrylic acid yield of about 72mol %, giving an overall acrylic acid yield in this reactivedistillation of about 75 mol %.

Procedure 1—Stability of Solid Material Samples in Liquid Chemicals

This procedure describes the treatment of solid material samples inliquid chemicals at certain temperatures and the related analysis. Thesolid material sample with a size of 15 mm×15 mm×2 mm is cleaned andanalyzed by weighing, optical microscopy and scanning electronmicroscopy in advance to the treatment. The treatment is performed in aborosilicate glass 3.3 vessel with 30 mm diameter and 200 mm height. 30ml liquid chemical is fed into the vessel covering the sample entirely.The chemical is stirred by a borosilicate glass 3.3 coated magnetic stirbar during the treatment to minimalize temperature and concentrationgradients. The sample is held in place by a support 15 mm above thevessel bottom to avoid mechanical contact with the stir bar. The vesselis open to atmosphere at the top through a vertical 1 meter long and 10mm diameter fluorinated ethylene propylene tube acting as a refluxcondenser at room temperature. The bottom half of the vessel isincluding the sample and the chemical is heated to a certain temperature“T” for a certain time “t”—individual for each treatment. After thetreatment, the sample is again cleaned and analyzed by weighing, opticalmicroscopy and scanning electron microscopy.

Example 71—Stability of Borosilicate Glass 3.3 (Boro 3.3) Versus2-Acetoxypropionic Acid (2-APA)

According to PROCEDURE 1, Boro 3.3 was tested for stability versus 2-APAat T=150° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. Boro 3.3 is stated as stable versus 2-APA up to at least 150°C.

Example 72—Stability of Quartz Glass (SiO₂) Versus 2-AcetoxypropionicAcid (2-APA)

According to PROCEDURE 1, SiO₂ was tested for stability versus 2-APA atT=150° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. SiO₂ is stated as stable versus 2-APA up to at least 150° C.

Example 73—Stability of Hastelloy C-276 (C-276) Versus2-Acetoxypropionic Acid (2-APA)

According to PROCEDURE 1, C-276 was tested for stability versus 2-APA atT=150° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. C-276 is stated as stable versus 2-APA up to at least 150° C.

Example 74—Stability of Stainless Steel 1.4571 (1.4571) Versus2-Acetoxypropionic Acid (2-APA)

According to PROCEDURE 1, 1.4571 was tested for stability versus 2-APAat T=150° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. 1.4571 is stated as stable versus 2-APA up to at least 150° C.

Example 75—Stability of Carbon Steel S235 (S235) Versus2-Acetoxypropionic Acid (2-APA)

According to PROCEDURE 1, S235 was tested for stability versus 2-APA atT=150° C. for t=24 h. Corrosion could be observed on the surface. S235is stated as not stable versus 2-APA at 150° C.

Example 76—Stability of Aluminum (Al) Versus 2-Acetoxypropionic Acid(2-APA)

According to PROCEDURE 1, Al was tested for stability versus 2-APA atT=150° C. for t=24 h. The mass change was less than 0.1% and no colorchange and no haptic change could be observed. The surface was slightlyroughened. Al is stated as stable with minor changes versus 2-APA up toat least 150° C.

Example 77—Stability of Polytetrafluorethylene (PTFE) Versus2-Acetoxypropionic Acid (2-APA)

According to PROCEDURE 1, PTFE was tested for stability versus 2-APA atT=150° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. PTFE is stated as stable versus 2-APA up to at least 150° C.

Example 78—Stability of Fluorinated Ethylene Propylene (FEP) Versus2-Acetoxypropionic Acid (2-APA)

According to PROCEDURE 1, FEP was tested for stability versus 2-APA atT=150° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. FEP is stated as stable versus 2-APA up to at least 150° C.

Example 79—Stability of Perfluoroalkoxy Alkane (PFA) Versus2-Acetoxypropionic Acid (2-APA)

According to PROCEDURE 1, PFA was tested for stability versus 2-APA atT=150° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. PFA is stated as stable versus 2-APA up to at least 150° C.

Example 80—Stability of Polyether Ether Ketone (PEEK) Versus2-Acetoxypropionic Acid (2-APA)

According to PROCEDURE 1, PEEK was tested for stability versus 2-APA atT=150° C. for t=24 h. The mass change was less than 0.1% and no surfacetopology change and no haptic change could be observed. The sampleshowed a slight change of its color. PEEK is stated as stable with minorchanges versus 2-APA up to at least 150° C.

Example 81—Stability of Fluoroelastomere (FKM) Versus 2-AcetoxypropionicAcid (2-APA)

According to PROCEDURE 1, FKM was tested for stability versus 2-APA atT=150° C. for t=24 h. The mass increase was more than 10% and the samplecracked. The chemical showed color changes. FKM is stated as not stableversus 2-APA at 150° C.

Example 82—Stability of Silicone Rubber (Sil) Versus 2-AcetoxypropionicAcid (2-APA)

According to PROCEDURE 1, Sil was tested for stability versus 2-APA atT=150° C. for t=24 h. The mass increase was less than 10% and reversibleafter drying and no surface topology change and no haptic change couldbe observed. Sil is stated as stable with minor changes versus 2-APA upto at least 150° C.

Example 83—Stability of Borosilicate Glass 3.3 (Boro 3.3) Versus2-Bromopropionic Acid (2-BrPA)

According to PROCEDURE 1, Boro 3.3 was tested for stability versus2-BrPA at T=100° C. for t=24 h. The mass change was less than 0.1% andno color change, no surface topology change and no haptic change couldbe observed. Boro 3.3 is stated as stable versus 2-BrPA up to at least100° C.

Example 84—Stability of Quartz Glass (SiO₂) Versus 2-Bromopropionic Acid(2-BrPA)

According to PROCEDURE 1, SiO₂ was tested for stability versus 2-BrPA atT=100° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. SiO₂ is stated as stable versus 2-BrPA up to at least 100° C.

Example 85—Stability of Stainless Steel 1.4571 (1.4571) Versus2-Bromopropionic Acid (2-BrPA)

According to PROCEDURE 1, 1.4571 was tested for stability versus 2-BrPAat T=100° C. for t=24 h. Corrosion could be observed on the surface.1.4571 is stated as not stable versus 2-BrPA at 100° C.

Example 86—Stability of Carbon Steel S235 (S235) Versus 2-BromopropionicAcid (2-BrPA)

According to PROCEDURE 1, S235 was tested for stability versus 2-BrPA atT=100° C. for t=24 h. Corrosion could be observed on the surface. S235is stated as not stable versus 2-BrPA at 100° C.

Example 87—Stability of Aluminum (Al) Versus 2-Bromopropionic Acid(2-BrPA)

According to PROCEDURE 1, Al was tested for stability versus 2-BrPA atT=100° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. Al is stated as stable versus 2-BrPA up to at least 100° C.

Example 88—Stability of Polytetrafluorethylene (PTFE) Versus2-Bromopropionic Acid (2-BrPA)

According to PROCEDURE 1, PTFE was tested for stability versus 2-BrPA atT=100° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. PTFE is stated as stable versus 2-BrPA up to at least 100° C.

Example 89—Stability of Fluorinated Ethylene Propylene (FEP) Versus2-Bromopropionic Acid (2-BrPA)

According to PROCEDURE 1, FEP was tested for stability versus 2-BrPA atT=100° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. FEP is stated as stable versus 2-BrPA up to at least 100° C.

Example 90—Stability of Perfluoroalkoxy Alkane (PFA) Versus2-Bromopropionic Acid (2-BrPA)

According to PROCEDURE 1, PFA was tested for stability versus 2-BrPA atT=100° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. PFA is stated as stable versus 2-BrPA up to at least 100° C.

Example 91—Stability of Polyether Ether Ketone (PEEK) Versus2-Bromopropionic Acid (2-BrPA)

According to PROCEDURE 1, PEEK was tested for stability versus 2-BrPA atT=100° C. for t=24 h. The mass change was less than 0.1% and no surfacetopology change and no haptic change could be observed. The sampleshowed a slight change of its color. PEEK is stated as stable with minorchanges versus 2-BrPA up to at least 100° C.

Example 92—Stability of Fluoroelastomere (FKM) Versus 2-BromopropionicAcid (2-BrPA)

According to PROCEDURE 1, FKM was tested for stability versus 2-BrPA atT=100° C. for t=24 h. The mass increase was more than 10%. The surfacewas roughened. FKM is stated as not stable versus 2-BrPA at 100° C.

Example 93—Stability of Silicone Rubber (Sil) Versus 2-BromopropionicAcid (2-BrPA)

According to PROCEDURE 1, Sil was tested for stability versus 2-BrPA atT=100° C. for t=24 h. The mass increase was more than 10%. The colorchanged. Sil is stated as not stable versus 2-BrPA at 100° C.

Example 94—Stability of Borosilicate Glass 3.3 (Boro 3.3) Versus AceticAcid 75 Weight Percent Aqueous Solution (AcOH75)

According to PROCEDURE 1, Boro 3.3 was tested for stability versusAcOH75 at T=90° C. for t=24 h. The mass change was less than 0.1% and nocolor change, no surface topology change and no haptic change could beobserved. Boro 3.3 is stated as stable versus AcOH75 up to at least 90°C.

Example 95—Stability of Quartz Glass (SiO₂) Versus Acetic Acid 75 WeightPercent Aqueous Solution (AcOH75)

According to PROCEDURE 1, SiO₂ was tested for stability versus AcOH75 atT=90° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. SiO₂ is stated as stable versus AcOH75 up to at least 90° C.

Example 96—Stability of Titanium Grade 2 (TiG2) Versus Acetic Acid 75Weight Percent Aqueous Solution (AcOH75)

According to PROCEDURE 1, TiG2 was tested for stability versus AcOH75 atT=90° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. TiG2 is stated as stable versus AcOH75 up to at least 90° C.

Example 97—Stability of Stainless Steel 1.4571 (1.4571) Versus AceticAcid 75 Weight Percent Aqueous Solution (AcOH75)

According to PROCEDURE 1, 1.4571 was tested for stability versus AcOH75at T=90° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. 1.4571 is stated as stable versus AcOH75 up to at least 90° C.

Example 98—Stability of Carbon Steel S235 (S235) Versus Acetic Acid 75Weight Percent Aqueous Solution (AcOH75)

According to PROCEDURE 1, S235 was tested for stability versus AcOH75 atT=90° C. for t=24 h. Corrosion could be observed on the surface. S235 isstated as not stable versus AcOH75 at 90° C.

Example 99—Stability of Aluminum (Al) Versus Acetic Acid 75 WeightPercent Aqueous Solution (AcOH75)

According to PROCEDURE 1, Al was tested for stability versus AcOH75 atT=90° C. for t=24 h. The mass change was less than 0.1%. Color changeand the surface was slightly roughened. Al is stated as not stableversus AcOH75 up to at least 90° C.

Example 100—Stability of Polytetrafluorethylene (PTFE) Versus AceticAcid 75 Weight Percent Aqueous Solution (AcOH75)

According to PROCEDURE 1, PTFE was tested for stability versus AcOH75 atT=90° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. PTFE is stated as stable versus AcOH75 up to at least 90° C.

Example 101—Stability of Fluorinated Ethylene Propylene (FEP) VersusAcetic Acid 75 Weight Percent Aqueous Solution (AcOH75)

According to PROCEDURE 1, FEP was tested for stability versus AcOH75 atT=90° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. FEP is stated as stable versus AcOH75 up to at least 90° C.

Example 102—Stability of Perfluoroalkoxy Alkane (PFA) Versus Acetic Acid75 Weight Percent Aqueous Solution (AcOH75)

According to PROCEDURE 1, PFA was tested for stability versus AcOH75 atT=90° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. PFA is stated as stable versus AcOH75 up to at least 90° C.

Example 103—Stability of Polyether Ether Ketone (PEEK) Versus AceticAcid 75 Weight Percent Aqueous Solution (AcOH75)

According to PROCEDURE 1, PEEK was tested for stability versus AcOH75 atT=90° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. PEEK is stated as stable versus AcOH75 up to at least 90° C.

Example 104—Stability of Fluoroelastomere (FKM) Versus Acetic Acid 75Weight Percent Aqueous Solution (AcOH75)

According to PROCEDURE 1, FKM was tested for stability versus AcOH75 atT=90° C. for t=24 h. The mass increase was more than 10% and the samplecracked. The chemical showed color changes. FKM is stated as not stableversus AcOH75 at 90° C.

Example 105—Stability of Silicone Rubber (Sil) Versus Acetic Acid 75Weight Percent Aqueous Solution (AcOH75)

According to PROCEDURE 1, Sil was tested for stability versus AcOH75 atT=90° C. for t=24 h. The mass increase was less than 10% and reversibleafter drying and no surface topology change and no haptic change couldbe observed. Sil is stated as stable with minor changes versus AcOH75 upto at least 90° C.

Example 106—Stability of Borosilicate Glass 3.3 (Boro 3.3) VersusAcrylic Acid (AA)

According to PROCEDURE 1, Boro 3.3 was tested for stability versus AA atT=20° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. Boro 3.3 is stated as stable versus AA up to at least 20° C.

Example 107—Stability of Quartz Glass (SiO₂) Versus Acrylic Acid (AA)

According to PROCEDURE 1, SiO₂ was tested for stability versus AA atT=20° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. SiO₂ is stated as stable versus AA up to at least 20° C.

Example 108—Stability of Titanium Grade 2 (TiG2) Versus Acrylic Acid(AA)

According to PROCEDURE 1, TiG2 was tested for stability versus AA atT=20° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. TiG2 is stated as stable versus AA up to at least 20° C.

Example 109—Stability of Stainless Steel 1.4571 (1.4571) Versus AcrylicAcid (AA)

According to PROCEDURE 1, 1.4571 was tested for stability versus AA atT=20° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. 1.4571 is stated as stable versus AA up to at least 20° C.

Example 110—Stability of Carbon Steel S235 (S235) Versus Acrylic Acid(AA)

According to PROCEDURE 1, S235 was tested for stability versus AA atT=20° C. for t=24 h. Corrosion could be observed on the surface. S235 isstated as not stable versus AA at 20° C.

Example 111—Stability of Aluminum (Al) Versus Acrylic Acid (AA)

According to PROCEDURE 1, Al was tested for stability versus AA at T=20°C. for t=24 h. The mass change was less than 0.1% and no color change,no surface topology change and no haptic change could be observed. Al isstated as stable versus AA up to at least 20° C.

Example 112—Stability of Polytetrafluorethylene (PTFE) Versus AcrylicAcid (AA)

According to PROCEDURE 1, PTFE was tested for stability versus AA atT=20° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. PTFE is stated as stable versus AA up to at least 20° C.

Example 113—Stability of Fluorinated Ethylene Propylene (FEP) VersusAcrylic Acid (AA)

According to PROCEDURE 1, FEP was tested for stability versus AA atT=20° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. FEP is stated as stable versus AA up to at least 20° C.

Example 114—Stability of Perfluoroalkoxy Alkane (PFA) Versus AcrylicAcid (AA)

According to PROCEDURE 1, PFA was tested for stability versus AA atT=20° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. PFA is stated as stable versus AA up to at least 20° C.

Example 115—Stability of Polyether Ether Ketone (PEEK) Versus AcrylicAcid (AA)

According to PROCEDURE 1, PEEK was tested for stability versus AA atT=20° C. for t=24 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. PEEK is stated as stable versus AA up to at least 20° C.

Example 116—Stability of Fluoroelastomere (FKM) Versus Acrylic Acid (AA)

According to PROCEDURE 1, FKM was tested for stability versus AA atT=20° C. for t=24 h. The mass increase was more than 10%. FKM is statedas not stable versus AA at 20° C.

Example 117—Stability of Silicone Rubber (Sil) Versus Acrylic Acid (AA)

According to PROCEDURE 1, Sil was tested for stability versus AA atT=20° C. for t=24 h. The mass increase was more than 10%. The colorchanged. Sil is stated as not stable versus AA at 20° C.

Example 118—Stability of Borosilicate Glass 3.3 (Boro 3.3) Versus LacticAcid 88 Weight Percent Aqueous Solution (LA88)

According to PROCEDURE 1, Boro 3.3 was tested for stability versus LA88at T=150° C. for t=168 h. The mass change was less than 0.1% and nocolor change, no surface topology change and no haptic change could beobserved. Boro 3.3 is stated as stable versus LA88 up to at least 150°C.

Example 119—Stability of Quartz Glass (SiO₂) Versus Lactic Acid 88Weight Percent Aqueous Solution (LA)

According to PROCEDURE 1, SiO₂ was tested for stability versus LA88 atT=150° C. for t=168 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. SiO₂ is stated as stable versus LA88 up to at least 150° C.

Example 120—Stability of Titanium Grade 2 (TiG2) Versus Lactic Acid 88Weight Percent Aqueous Solution (LA)

According to PROCEDURE 1, TiG2 was tested for stability versus LA88 atT=150° C. for t=168 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. TiG2 is stated as stable versus LA88 up to at least 150° C.

Example 121—Stability of Hastelloy C-276 (C-276) Versus Lactic Acid 88Weight Percent Aqueous Solution (LA)

According to PROCEDURE 1, C-276 was tested for stability versus LA88 atT=150° C. for t=168 h. Corrosion could be observed on the surface. C-276is stated as not stable versus LA88 at 150° C.

Example 122—Stability of Carbon Steel S235 (S235) Versus Lactic Acid 88Weight Percent Aqueous Solution (LA)

According to PROCEDURE 1, S235 was tested for stability versus LA88 atT=150° C. for t=168 h. Corrosion could be observed on the surface. S235is stated as not stable versus LA88 at 150° C.

Example 123—Stability of Aluminum (Al) Versus Lactic Acid 88 WeightPercent Aqueous Solution (LA)

According to PROCEDURE 1, Al was tested for stability versus LA88 atT=150° C. for t=168 h. The mass change was less than 0.1%. Color changecould be observed. The surface was slightly roughened. Al is stated asstable with minor changes versus LA88 up to at least 150° C.

Example 124—Stability of Polytetrafluorethylene (PTFE) Versus LacticAcid 88 Weight Percent Aqueous Solution (LA)

According to PROCEDURE 1, PTFE was tested for stability versus LA88 atT=150° C. for t=168 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. PTFE is stated as stable versus LA88 up to at least 150° C.

Example 125—Stability of Fluorinated Ethylene Propylene (FEP) VersusLactic Acid 88 Weight Percent Aqueous Solution (LA)

According to PROCEDURE 1, FEP was tested for stability versus LA88 atT=150° C. for t=168 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. FEP is stated as stable versus LA88 up to at least 150° C.

Example 126—Stability of Perfluoroalkoxy Alkane (PFA) Versus Lactic Acid88 Weight Percent Aqueous Solution (LA)

According to PROCEDURE 1, PFA was tested for stability versus LA88 atT=150° C. for t=168 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. PFA is stated as stable versus LA88 up to at least 150° C.

Example 127—Stability of Polyether Ether Ketone (PEEK) Versus LacticAcid 88 Weight Percent Aqueous Solution (LA)

According to PROCEDURE 1, PEEK was tested for stability versus LA88 atT=150° C. for t=168 h. The mass change was less than 0.1% and no colorchange, no surface topology change and no haptic change could beobserved. PEEK is stated as stable versus LA88 up to at least 150° C.

Example 128—Stability of Perfluoroelastomer (FFKM) Versus Lactic Acid 88Weight Percent Aqueous Solution (LA)

According to PROCEDURE 1, FFKM was tested for stability versus LA88 atT=150° C. for t=168 h. The mass increase was less than 10% and no colorchange could be observed. FFKM is stated as stable with minor changesversus LA88 up to at least 150° C.

Example 129—Stability of Fluoroelastomere (FKM) Versus Lactic Acid 88Weight Percent Aqueous Solution (LA)

According to PROCEDURE 1, FKM was tested for stability versus LA88 atT=150° C. for t=168 h. The mass increase was more than 10%. FKM isstated as not stable versus LA88 at 150° C.

Example 130—Stability of Silicone Rubber (Sil) Versus Lactic Acid 88Weight Percent Aqueous Solution (LA)

According to PROCEDURE 1, Sil was tested for stability versus LA88 atT=250° C. for t=168 h. The mass increase was more than 10%. The colorchanged. Sil is stated as not stable versus LA88 at 250° C.

Example 131—Stability of Borosilicate Glass 3.3 (Boro 3.3) VersusTetrabutylphosphonium Bromide ([PBu₄]Br)

According to PROCEDURE 1, Boro 3.3 was tested for stability versus[PBu₄]Br at T=250° C. for t=168 h. The mass change was less than 0.1%and no color change, no surface topology change and no haptic changecould be observed. Boro 3.3 is stated as stable versus [PBu₄]Br up to atleast 250° C.

Example 132—Stability of Quartz Glass (SiO₂) VersusTetrabutylphosphonium Bromide ([PBu₄]Br)

According to PROCEDURE 1, SiO₂ was tested for stability versus [PBu₄]Brat T=250° C. for t=168 h. The mass change was less than 0.1% and nosurface topology change and no haptic change could be observed. Thecolor of the chemical changes slightly. SiO₂ is stated as stable withminor changes versus [PBu₄]Br up to at least 250° C.

Example 133—Stability of Titanium Grade 2 (TiG2) VersusTetrabutylphosphonium Bromide ([PBu₄]Br)

According to PROCEDURE 1, TiG2 was tested for stability versus [PBu₄]Brat T=250° C. for t=168 h. Corrosion could be observed. TiG2 is stated asnot stable versus [PBu₄]Br at 250° C.

Example 134—Stability of Hastelloy C-276 (C-276) VersusTetrabutylphosphonium Bromide ([PBu₄]Br)

According to PROCEDURE 1, C-276 was tested for stability versus [PBu₄]Brat T=250° C. for t=168 h. Corrosion could be observed. C-276 is statedas not stable versus [PBu₄]Br at 250° C.

Example 135—Stability of Stainless Steel 1.4571 (1.4571) VersusTetrabutylphosphonium Bromide ([PBu₄]Br)

According to PROCEDURE 1, 1.4571 was tested for stability versus[PBu₄]Br at T=250° C. for t=168 h. Corrosion could be observed. 1.4571is stated as not stable versus [PBu₄]Br at 250° C.

Example 136—Stability of Aluminum (Al) Versus TetrabutylphosphoniumBromide ([PBu₄]Br)

According to PROCEDURE 1, Al was tested for stability versus [PBu₄]Br atT=250° C. for t=168 h. Corrosion could be observed. Al is stated as notstable versus [PBu₄]Br at 250° C.

Example 137—Stability of Polytetrafluorethylene (PTFE) VersusTetrabutylphosphonium Bromide ([PBu₄]Br)

According to PROCEDURE 1, PTFE was tested for stability versus [PBu₄]Brat T=250° C. for t=168 h. The mass change was less than 0.1% and nocolor change, no surface topology change and no haptic change could beobserved. PTFE is stated as stable versus [PBu₄]Br up to at least 250°C.

Example 138—Stability of Perfluoroalkoxy Alkane (PFA) VersusTetrabutylphosphonium Bromide ([PBu₄]Br)

According to PROCEDURE 1, PFA was tested for stability versus [PBu₄]Brat T=250° C. for t=168 h. The mass change was less than 0.1% and nocolor change, no surface topology change and no haptic change could beobserved. PFA is stated as stable versus [PBu₄]Br up to at least 250° C.

Example 139—Stability of Perfluoroelastomer (FFKM) VersusTetrabutylphosphonium Bromide ([PBu₄]Br)

According to PROCEDURE 1, FFKM was tested for stability versus [PBu₄]Brat T=250° C. for t=168 h. The mass increase was less than 10% and nocolor change could be observed. FFKM is stated as stable with minorchanges versus [PBu₄]Br up to at least 250° C.

Example 140—Stability of Fluoroelastomere (FKM) VersusTetrabutylphosphonium Bromide ([PBu₄]Br)

According to PROCEDURE 1, FKM was tested for stability versus [PBu₄]Brat T=250° C. for t=168 h. The mass increase was more than 10%. FKM isstated as not stable versus [PBu₄]Br at 250° C.

The foregoing description is given for clearness of understanding only,and no unnecessary limitations should be understood therefrom, asmodifications within the scope of the invention may be apparent to thosehaving ordinary skill in the art.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application, is hereby incorporated herein by reference in itsentirety unless expressly excluded or otherwise limited. The citation ofany document is not an admission that it is prior art with respect toany invention disclosed or claimed herein or that it alone, or in anycombination with any other reference or references, teaches, suggests ordiscloses any such invention. Further, to the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A method of making acrylic acid comprisingcontacting a feed stream comprising lactide with a molten salt catalystin a reactor at about 190° C.; wherein said molten salt catalystcomprises [PBu₄]Br and 2-BrPA; wherein the molar ratio of lactic acidequivalent to [PBu₄]Br to 2-BrPA is about 1:2:0.1; whereby acrylic acidis produced as a result of said contacting in said reactor and isremoved in-situ via a reactive distillation at about 10 mbar; andwherein said acrylic acid is produced at a yield of at least about 50%.